ABCMdb

ABCA4 p.Val2050Leu

ClinVar:	c.6148G>C , p.Val2050Leu ? , Conflicting interpretations of pathogenicity, not provided
Predicted by SNAP2:	A: N (61%), C: N (61%), D: D (66%), E: D (85%), F: N (57%), G: D (63%), H: N (61%), I: N (93%), K: D (53%), L: D (85%), M: N (78%), N: N (53%), P: D (53%), Q: N (61%), R: D (53%), S: N (57%), T: N (72%), W: D (66%), Y: N (57%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: D, R: D, S: D, T: N, W: D, Y: D,

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[hide] Organization of the ABCR gene: analysis of promote... Gene. 1998 Jul 17;215(1):111-22. Allikmets R, Wasserman WW, Hutchinson A, Smallwood P, Nathans J, Rogan PK, Schneider TD, Dean M
Organization of the ABCR gene: analysis of promoter and splice junction sequences.
Gene. 1998 Jul 17;215(1):111-22., [PMID:9666097]

Abstract [show]
Mutations in the human ABCR gene have been associated with the autosomal recessive Stargardt disease (STGD), retinitis pigmentosa (RP19), and cone-rod dystrophy (CRD) and have also been found in a fraction of age-related macular degeneration (AMD) patients. The ABCR gene is a member of the ATP-binding cassette (ABC) transporter superfamily and encodes a rod photoreceptor-specific membrane protein. The cytogenetic location of the ABCR gene was refined to 1p22.3-1p22.2. The intron/exon structure was determined for the ABCR gene from overlapping genomic clones. ABCR spans over 100kb and comprises 50 exons. Intron/exon splice site sequences are presented for all exons and analyzed for information content (Ri). Nine splice site sequence variants found in STGD and AMD patients are evaluated as potential mutations. The localization of splice sites reveals a high degree of conservation between other members of the ABC1 subfamily, e.g. the mouse Abc1 gene. Analysis of the 870-bp 5' upstream of the transcription start sequence reveals multiple putative photoreceptor-specific regulatory elements including a novel retina-specific transcription factor binding site. These results will be useful in further mutational screening of the ABCR gene in various retinopathies and for determining the substrate and/or function of this photoreceptor-specific ABC transporter.

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122 acceptors (G863A, 5585+1G/A, V2050L), and six in The mean of the distribution of individual information donors (4253+5G/T, 5196+1G/A, 5196+2T/C, contents (R i values, R sequence ) for splice acceptor and 5714+5G/A, 5898+1G/T, 6005+1G/T). Login to comment
130 The V2050L muta-For the 50 splice acceptor and donor sites of the tion lowered the information content of the spliceABCR gene, the average R i values were 9.49±0.37 and acceptor site in exon 45 insignificantly, suggesting that7.45±0.32, respectively, in good correlation with those this variant did not affect splicing but represented apredicted. Login to comment
135 The individual information R i acceptor at position 365 by two bits and created an Table 2 Analysis of ABCR splice site variants Exon Mutation Disease Number of patients wt R i mt R i Predicted effect on the ABCR protein 17A G863A STGD/AMD 11/1 11.6 9.7 Change of aa or deletion of one aaa 28D 4253+5G/T STGD 1 8.2 4.3 Partially functioning splice site 36D 5196+1G/A AMD 1 6.8 -6.0 Non-functional protein 36D 5196+2T/C STGD 1 6.8 -0.7 Non-functional protein 40A 55851G/A STGD 1 5.9 -1.6 Non-functional protein 40D 5714+5G/A STGD 8 7.2 3.7 Partially functioning splice site 42D 5898+1G/T STGD 3 8.6 0.8 Non-functional protein 43D 6005+1G/T STGD 1 11.2 3.4 Partially functioning splice site 45A V2050L STGD 2 12.5 10.6 Change of aa, no effect on splicing 'A` or 'D` after the exon number indicates splice acceptor or donor sequences, respectively. Login to comment
126 acceptors (G863A, 5585+1G/A, V2050L), and six in The mean of the distribution of individual information donors (4253+5G/T, 5196+1G/A, 5196+2T/C, contents (R i values, R sequence ) for splice acceptor and 5714+5G/A, 5898+1G/T, 6005+1G/T). Login to comment
141 The individual information R i acceptor at position 365 by two bits and created an Table 2 Analysis of ABCR splice site variants Exon Mutation Disease Number of patients wt R i mt R i Predicted effect on the ABCR protein 17A G863A STGD/AMD 11/1 11.6 9.7 Change of aa or deletion of one aaa 28D 4253+5G/T STGD 1 8.2 4.3 Partially functioning splice site 36D 5196+1G/A AMD 1 6.8 -6.0 Non-functional protein 36D 5196+2T/C STGD 1 6.8 -0.7 Non-functional protein 40A 55851G/A STGD 1 5.9 -1.6 Non-functional protein 40D 5714+5G/A STGD 8 7.2 3.7 Partially functioning splice site 42D 5898+1G/T STGD 3 8.6 0.8 Non-functional protein 43D 6005+1G/T STGD 1 11.2 3.4 Partially functioning splice site 45A V2050L STGD 2 12.5 10.6 Change of aa, no effect on splicing 'A` or 'D` after the exon number indicates splice acceptor or donor sequences, respectively. Login to comment

[hide] A subgroup of age-related macular degeneration is ... Invest Ophthalmol Vis Sci. 2012 Apr 30;53(4):2112-8. doi: 10.1167/iovs.11-8785. Print 2012 Apr. Fritsche LG, Fleckenstein M, Fiebig BS, Schmitz-Valckenberg S, Bindewald-Wittich A, Keilhauer CN, Renner AB, Mackensen F, Mossner A, Pauleikhoff D, Adrion C, Mansmann U, Scholl HP, Holz FG, Weber BH
A subgroup of age-related macular degeneration is associated with mono-allelic sequence variants in the ABCA4 gene.
Invest Ophthalmol Vis Sci. 2012 Apr 30;53(4):2112-8. doi: 10.1167/iovs.11-8785. Print 2012 Apr., [PMID:22427542]

Abstract [show]
Purpose. Age-related macular degeneration (AMD) is a heterogeneous condition of high prevalence and complex etiology involving genetic as well as environmental factors. By fundus autofluorescence (FAF) imaging, AMD can be classified into several distinct phenotypes, with one subgroup characterized by fine granular pattern with peripheral punctate spots (GPS[+]). Some features of GPS[+] overlap with Stargardt disease (STGD1), a recessive macular dystrophy caused by biallelic sequence variants in the ATP-binding cassette transporter 4 (ABCA4) gene. The aim of this study was to investigate the role of ABCA4 in GPS[+]. Methods. The ABCA4 gene was sequenced in 25 patients with the GPS[+] phenotype and 29 with geographic atrophy (GA)-AMD but no signs of GPS (GPS[-]). In addition, frequencies of risk-increasing alleles at three known AMD susceptibility loci, including complement factor H (CFH), age-related maculopathy susceptibility 2 (ARMS2), and complement component 3 (C3), were evaluated. Results. We demonstrate that GPS[+] is associated significantly with monoallelic ABCA4 sequence variants. Moreover, frequencies of AMD risk-increasing alleles at CFH, ARMS2, and C3 are similar in GPS[+] and STGD1 patients, with risk allele frequencies in both subcategories comparable to population-based control individuals estimated from 3,510 individuals from the NHLBI Exome Sequencing Project. Conclusions. Our data suggest that the GPS[+] phenotype is accounted for by monoallelic variants in ABCA4 and unlikely by the well-established AMD risk-increasing alleles at CFH, ARMS2, and C3. These findings provide support for a complex role of ABCA4 in the etiology of a minor proportion of patients with AMD.

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93 These patients were heterozygous for variants c.634C>T (p.R212C), c.4556C>G (p.T1519R), and c.6148G>C (p.V2050L), respectively. Login to comment
91 These patients were heterozygous for variants c.634C>T (p.R212C), c.4556C>G (p.T1519R), and c.6148G>C (p.V2050L), respectively. Login to comment

[hide] ABCA4 and ROM1: implications for modification of t... Invest Ophthalmol Vis Sci. 2010 Aug;51(8):4253-65. Epub 2010 Mar 24. Poloschek CM, Bach M, Lagreze WA, Glaus E, Lemke JR, Berger W, Neidhardt J
ABCA4 and ROM1: implications for modification of the PRPH2-associated macular dystrophy phenotype.
Invest Ophthalmol Vis Sci. 2010 Aug;51(8):4253-65. Epub 2010 Mar 24., [PMID:20335603]

Abstract [show]
PURPOSE: To identify the causative mutation leading to autosomal dominant macular dystrophy, cone dystrophy, and cone-rod dystrophy in a five-generation family and to explain the high intrafamilial phenotypic variation by identifying possible modifier genes. METHODS: Fifteen family members were investigated by detailed ophthalmic and electrophysiologic phenotyping. Mutation screening was initially performed with microarrays that detect known mutations in genes associated with retinal degeneration. Furthermore, the patients' genomic DNA was analyzed by sequencing analysis of PRPH2, ABCA4, and ROM1. RESULTS: Heterozygous mutations were identified in three genes and showed five different combinations within the studied family. All clearly affected family members carried the heterozygous PRPH2 mutation p.R172W. Patients with heterozygous sequence alterations only in ROM1 (p.R229H) or ABCA4 (p.V2050L) showed a mild ocular phenotype and were otherwise asymptomatic. The phenotypic severity of patients carrying the PRPH2 mutation increased with an additional mutation in ROM1. Patients carrying all three mutations were the most severely affected. CONCLUSIONS: Features of a PRPH2-associated phenotype might be modulated by additional mutations in other genes (in this family ABCA4 and/or ROM1) accounting for intrafamilial variability and resulting in a cumulative effect worsening the phenotype. Families showing a variable macular dystrophy phenotype caused by mutations in PRPH2 should be tested for additional mutations in ABCA4 and ROM1, as they may alter the progression of the PRPH2 phenotype. This testing will influence genetic counseling, as patients with additional mutations may be confronted with a faster progression of visual loss.

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9 Patients with heterozygous sequence alterations only in ROM1 (p.R229H) or ABCA4 (p.V2050L) showed a mild ocular phenotype and were otherwise asymptomatic. Login to comment
73 It is predicted to lead to an amino acid substitution (valine to leucine at position 2050, p.V2050L). Login to comment
103 Group 3: Mutations in PRPH2, ROM1, and ABCA4 (p.R172W, p.R229H, and p.V2050L). Login to comment
124 Group 5: Mutation of ABCA4 (p.V2050L). Login to comment
141 TABLE1.DetailedPhenotypicDataofAllExaminedFamilyMembersSortedbyGroups Patient Group Genotype Age AtEx. VA OD/OS Age(y)at Onsetof SymptomsVisualField ColorVision (PanelD15)FundusFAF ERG Scotopic 1.8B-Wave Amplitude ERG30-Hz Flicker AmplitudemfERG EOG Arden Ratio V-21 p.R172W 221.25/1.25AsymptomaticOP:ODnasalsup smallscotoma, OSnormal;GP: ODnormal ODdesaturated:2 unspecific defects OU:ONdrusen, perifoveolar drusenODϾOS OU:ONdrusen, peri-foveolar punctual increase ODϾOS P1NNODN OSdesaturated:1 unspecific defect OSNA IV-71 p.R172W 450.2/0.140;VAloss35; photophobia GP:OUcentral scotoma40° (I/2) OD:mildprotan, deutanand tritandefects, OS:unspecific defects OU:macularRPE granularity,OS: 0.5ODD temporalMA OU:speckled beyondarcades; OS:reducedat lowerarcade indicating atrophy,1ODD NNZ5ND* III-41 p.R172W 750.05/0.0742;VAloss photophobia (onset unknown) GP:OUcentral scotoma30° (I/3) OU:marked protanand deutandefects OU:severeMA, 4ODD OU:reduced CTA,4ODD, surrounding speckles NP2AP1 V-12 p.R172W, p.R229H 260.9/0.922;flickering lightsensation OP:ODnormal OSparacentral defects10° fromcenter OU:normalOU:mildmacular RPEclumping OU:speckled, 2ODD, surrounding increase,OD: reticular increase P1P1Z3N 21AsymptomaticNReNReNReNDNDNDZ1ND IV-12 p.R172W, p.R229H 560.8/0.7501adaptation difficulties GP:OUparacentral scotoma:1-10° radius(I/2,I/3 inf,I/4sup) OU:mild unspecific defectsOS:1 tritandefect OU:mildRPE atrophy OU:speckled, 3ODD NP1Z4P1 32;photophobiaOP:asinGPOD:moderate temporaloptic nerveatrophy 30;flickering lightsensation, relative paracentral scotoma 471.0/1.032;photophobiaGP:OUstableNDOU:mildRPE irregularity NDNDNDZ3ND 430.9/0.930;flickering lightsensation, relative paracentral scotoma GP:OU paracentral scotoma:3-10° radius(I/2inf, I/4sup) OU:moderate tetartandefects OU:minorRPE irregularity NDP2NNDP1 (continues) TABLE1(continued).DetailedPhenotypicDataofAllExaminedFamilyMembersSortedbyGroups Patient Group Genotype Age AtEx. VA OD/OS Age(y)at Onsetof SymptomsVisualField ColorVision (PanelD15)FundusFAF ERG Scotopic 1.8B-Wave Amplitude ERG30-Hz Flicker AmplitudemfERG EOG Arden Ratio III-22 p.R172W, p.R229H 840.05/0.0256;photophobia 30;VAloss GPstableOU:notpossibleOU:severeMAOU:NRdueto dense cataracts P2P2Z4P2 710.02/0.03GP:OUsupVF loss,OSinf,VF constriction to70° OU:notpossibleOU:severeMANDNDNDNDND V-43 p.R172W, p.V2050L, p.R229H 221.0/1.222;photophobia inbrightlight 22;mild nyctalopia GP:OUsupmild constriction (I/3,I/2,I/1), OSparacentral scotoma5° (I/1),OP: reduction central20° OU:normalOU:mild- moderateMA OU:speckled,3 ODD, encircling increase P1NZ3N IV-43 p.R172W, p.V2050L, p.R229H 500.2/0.349;nyctalopia 40;photophobia 35;VFdefects 13;mildVAloss GP:OD paracentral scotoma(III/4) 10°,sensitivity lossforI/1,I/2, OScentral scotoma40° (I/3)extending temporally OU:marked protanand deutandefects OU:moderateMA extendingbeyond arcades; temporallyϾ1 ODDsevereMA; midperipheral RPEclumping; moderate temporalON atrophy OU:speckled beyond arcades, reducedCTA (mild progression) P3P2Z5P1 480.2/0.540;photophobia 35;VFdefects 13;mildVAloss GP:ODcentral scotoma35° (I/3)extending temporally,OS centralscotoma 40°(I/3) OD:marked protanand deutandefects OS:marked protan,deutan, andtritan defects OU:mild pericentralMAto arcades;mid- peripheralRPE clumping;nasally 1ODDRPE atrophy; moderate temporalON atrophy OU:speckled beyond arcades, reducedCTA P2P2Z5ND IV-94 p.R229H 361.25/1.25AsymptomaticOPandGP: normal OS:unsaturated:2 unspecific defects OU:normalOU:normalNNZ1N (continues) nantly affected with stable rod function. Login to comment
155 The ABCA4 p.V2050L heterozygous carrier reported herein (group 5, V-3) showed centrally reduced mfERG amplitudes and additional minor fundus abnormalities. Login to comment
156 This finding suggests that the p.V2050L mutation in the heterozygous state is capable of mildly reducing macular function without an additional mutation on the second allele. Login to comment
157 Indeed, heterozygous mutations in ABCA4 have been reported to cause electrophysiologically detectable dysfunction in individuals who had no obvious clinical signs: Maia-Lopes et al.40 described and clinically characterized a heterozygous ABCA4 p.V2050L carrier within a family with Stargardt disease. Login to comment
160 In contrast, normal flicker amplitudes and stable rod function as shown in a follow-up examination 13 years after the initial presentation was found in her brother (group 2, IV-1) not carrying ABCA4 p.V2050L. Login to comment
161 This finding may hint at an additional effect of p.V2050L on generalized cone function and an acceleration of loss of rod function if the genotype also contains ROM1 p.R229H and PRPH2 TABLE1(continued).DetailedPhenotypicDataofAllExaminedFamilyMembersSortedbyGroups Patient Group Genotype AgeAt Ex. VA OD/OS Age(y)at Onsetof SymptomsVisualField ColorVision (PanelD15)FundusFAF ERG Scotopic 1.8B-Wave Amplitude ERG30-Hz Flicker AmplitudemfERG EOG Arden Ratio III-64 p.R229H 681.0/1.0AsymptomaticOPandGP: normal OS:unsaturated:1 unspecific defect OU:mildarteriolar narrowing; arteriovenous nipping OU:normalNNZ2N V-35 p.V2050L 241.25/1.25AsymptomaticOPandGP: Normal ODdesaturated:1 unspecific defect OU:minimal perifoveolarRPE irregularity OU:subtle perifoveolar increase NNZ2N A,globalamplitudereduction;arcades,temporalvasculararcades;CTA,correspondingtoatrophy;EOG,electrooculogram;ERG,full-fieldelectroretinogram;ex.,examination;FAF,fundus autofluorescence;GP,Goldmannperimetry;inf,inferior;MA,macularatrophy;mfERG,multifocalelectroretinogram;NA,notanalyzableduetoartifact;N,normal;ND,notdone;ND*,notdonebecause patientrefusedtheexamination;NL,normallimit;NR,notrecordable;NR,norecords;ON,opticnerve;OP,Octopusperimetry;P1-3,amplitude(ERG)orArdenratio(EOG,normalrange1.7-3.3) belowthelowernormallimit(increasingreduction);ODD,opticdiscdiameter;sup,superior;VA,visualacuity;VF,visualfield;Z1-5,pleaseseeMethodsforanexplanation.Alldegreesindicate diameterunlessotherwiseindicated. Login to comment
163 In support of this idea, it has been reported previously that ABCA4 p.V2050L can be associated with a rod-cone pattern of functional loss as described in one patient with RP who bears a heterozygous p.V2050L mutation. Login to comment
70 It is predicted to lead to an amino acid substitution (valine to leucine at position 2050, p.V2050L). Login to comment
100 Group 3: Mutations in PRPH2, ROM1, and ABCA4 (p.R172W, p.R229H, and p.V2050L). Login to comment
121 Group 5: Mutation of ABCA4 (p.V2050L). Login to comment
140 Detailed Phenotypic Data of All Examined Family Members Sorted by Groups Patient Group Genotype Age At Ex. VA OD/OS Age (y) at Onset of Symptoms Visual Field Color Vision (Panel D 15) Fundus FAF ERG Scotopic 1.8 B-Wave Amplitude ERG 30-Hz Flicker Amplitude mfERG EOG Arden Ratio III-2 2 p.R172W, p.R229H 84 0.05/0.02 56; photophobia 30; VA loss GP stable OU: not possible OU: severe MA OU: NR due to dense cataracts P 2 P 2 Z 4 P 2 71 0.02/0.03 GP: OU sup VF loss, OS inf, VF constriction to 70&#b0; OU: not possible OU: severe MA ND ND ND ND ND V-4 3 p.R172W, p.V2050L, p.R229H 22 1.0/1.2 22; photophobia in bright light 22; mild nyctalopia GP: OU sup mild constriction (I/3, I/2, I/1), OS paracentral scotoma 5&#b0; (I/1), OP: reduction central 20&#b0; OU: normal OU: mild-moderate MA OU: speckled, 3 ODD, encircling increase P 1 N Z 3 N IV-4 3 p.R172W, p.V2050L, p.R229H 50 0.2/0.3 49; nyctalopia 40; photophobia 35; VF defects 13; mild VA loss GP: OD paracentral scotoma (III/4) 10&#b0;, sensitivity loss for I/1, I/2, OS central scotoma 40&#b0; (I/3) extending temporally OU: marked protan and deutan defects OU: moderate MA extending beyond arcades; temporally b0e;1 ODD severe MA; midperipheral RPE clumping; moderate temporal ON atrophy OU: speckled beyond arcades, reduced CTA (mild progression) P 3 P 2 Z 5 P 1 48 0.2/0.5 40; photophobia 35; VF defects 13; mild VA loss GP: OD central scotoma 35&#b0; (I/3) extending temporally, OS central scotoma 40&#b0; (I/3) OD: marked protan and deutan defects OS: marked protan, deutan, and tritan defects OU: mild pericentral MA to arcades; mid-peripheral RPE clumping; nasally 1 ODD RPE atrophy; moderate temporal ON atrophy OU: speckled beyond arcades, reduced CTA P 2 P 2 Z 5 ND IV-9 4 p.R229H 36 1.25/1.25 Asymptomatic OP and GP: normal OS: unsaturated: 2 unspecific defects OU: normal OU: normal N N Z 1 N (continues) nantly affected with stable rod function. Login to comment
154 The ABCA4 p.V2050L heterozygous carrier reported herein (group 5, V-3) showed centrally reduced mfERG amplitudes and additional minor fundus abnormalities. Login to comment
159 In contrast, normal flicker amplitudes and stable rod function as shown in a follow-up examination 13 years after the initial presentation was found in her brother (group 2, IV-1) not carrying ABCA4 p.V2050L. Login to comment
164 In support of this idea, it has been reported previously that ABCA4 p.V2050L can be associated with a rod-cone pattern of functional loss as described in one patient with RP who bears a heterozygous p.V2050L mutation. Login to comment

[hide] Frequency of ABCA4 mutations in 278 Spanish contro... Br J Ophthalmol. 2009 Oct;93(10):1359-64. Epub 2008 Oct 31. Riveiro-Alvarez R, Aguirre-Lamban J, Lopez-Martinez MA, Trujillo-Tiebas MJ, Cantalapiedra D, Vallespin E, Avila-Fernandez A, Ramos C, Ayuso C
Frequency of ABCA4 mutations in 278 Spanish controls: an insight into the prevalence of autosomal recessive Stargardt disease.
Br J Ophthalmol. 2009 Oct;93(10):1359-64. Epub 2008 Oct 31., [PMID:18977788]

Abstract [show]
AIM: To determine the carrier frequency of ABCA4 mutations in order to achieve an insight into the prevalence of autosomal recessive Stargardt disease (arSTGD) in the Spanish population. METHODS: arSTGD patients (n = 133) were analysed using ABCR400 microarray and sequencing. Control subjects were analysed by two different strategies: 200 individuals were screened for the p.Arg1129Leu mutation by denaturing-HPLC and sequencing; 78 individuals were tested for variants with the microarray and sequencing. RESULTS: For the first strategy in control subjects, the p.Arg1129Leu variant was found in two heterozygous individuals, which would mean a carrier frequency for any variant of approximately 6.0% and a calculated arSTGD prevalence of 1:1000. For the second strategy, carrier frequency was 6.4% and therefore an estimated prevalence of the disease of 1:870. CONCLUSION: Calculated prevalence of arSTGD based on the ABCA4 carrier frequency could be considerably higher than previous estimation. This discrepancy between observed (genotypic) and estimated (phenotypic) prevalence could be due to the existence of non-pathological or low penetrance alleles, which may result in late-onset arSTGD or may be implicated in age-related macular degeneration. This situation should be regarded with special care when genetic counselling is given and further follow-up of these patients should be recommended.

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96 These Table 1 ABCA4 sequence variants identified in Spanish control population Mutant alleles Nucleotide change Amino acid change Number of cases Number of alleles Frequency (%) Homozygous individuals Mutations* c.661G.A p.Gly221Arg 1 1 0.64 None c.1140T.A p.Asn380Lys 1 1 0.64 None c.2588G.C p.Gly863Ala 1 1 0.64 None c.3113C.T p.Ala1038Val 1 1 0.64 None c.3899G.A p.Arg1300Gln 1 1 0.64 None c.5882G.A p.Gly1961Glu 1 1 0.64 None c.5908C.T p.Leu1970Phe 1 1 0.64 None c.6148G.C p.Val2050Leu 1 1 0.64 None c.6529G.A p.Asp2177Asn 2 2 1.28 None Total 10 Polymorphisms{ c.466A.G p.Ile156Val 5 5 3.2 None c.635G.A p.Arg212His 5 6 3.84 1 c.1268A.G p.His423Arg 43 48 30.7 5 c.1269C.T p.His423His 2 2 1.28 None IVS10+5delG 34 36 23 2 c.2828G.A p.Arg943Gln 1 1 0.64 None c.4203C.A p.Pro1401Pro 3 3 1.9 None IVS33+48C.T 59 75 48 16 c.5603A.T p.Asn1868Ile 4 4 2.5 None c.5682G.C p.Leu1894Leu 29 35 22.4 6 c.5814A.G p.Leu1938Leu 27 33 21.1 6 c.5843 C.T p.Pro1948Leu 9 10 6.4 1 c.5844A.G p.Pro1948Pro 27 32 20.5 5 c.6069C.T p.Ile2023Ile 11 12 7.7 1 c.6249C.T p.Ile2083Ile 12 14 8.9 2 c.6285T.C p.Asp2095Asp 24 26 16.6 2 c.6764G.T p.Ser2255Ile 12 13 8.3 1 *A total of 15 mutant alleles were detected. Login to comment
97 These Table 1 ABCA4 sequence variants identified in Spanish control population Mutant alleles Nucleotide change Amino acid change Number of cases Number of alleles Frequency (%) Homozygous individuals Mutations* c.661G.A p.Gly221Arg 1 1 0.64 None c.1140T.A p.Asn380Lys 1 1 0.64 None c.2588G.C p.Gly863Ala 1 1 0.64 None c.3113C.T p.Ala1038Val 1 1 0.64 None c.3899G.A p.Arg1300Gln 1 1 0.64 None c.5882G.A p.Gly1961Glu 1 1 0.64 None c.5908C.T p.Leu1970Phe 1 1 0.64 None c.6148G.C p.Val2050Leu 1 1 0.64 None c.6529G.A p.Asp2177Asn 2 2 1.28 None Total 10 Polymorphisms{ c.466A.G p.Ile156Val 5 5 3.2 None c.635G.A p.Arg212His 5 6 3.84 1 c.1268A.G p.His423Arg 43 48 30.7 5 c.1269C.T p.His423His 2 2 1.28 None IVS10+5delG 34 36 23 2 c.2828G.A p.Arg943Gln 1 1 0.64 None c.4203C.A p.Pro1401Pro 3 3 1.9 None IVS33+48C.T 59 75 48 16 c.5603A.T p.Asn1868Ile 4 4 2.5 None c.5682G.C p.Leu1894Leu 29 35 22.4 6 c.5814A.G p.Leu1938Leu 27 33 21.1 6 c.5843 C.T p.Pro1948Leu 9 10 6.4 1 c.5844A.G p.Pro1948Pro 27 32 20.5 5 c.6069C.T p.Ile2023Ile 11 12 7.7 1 c.6249C.T p.Ile2083Ile 12 14 8.9 2 c.6285T.C p.Asp2095Asp 24 26 16.6 2 c.6764G.T p.Ser2255Ile 12 13 8.3 1 *A total of 15 mutant alleles were detected. Login to comment

[hide] ABCA4 gene analysis in patients with autosomal rec... Eur J Hum Genet. 2008 Jul;16(7):812-9. Epub 2008 Feb 20. Kitiratschky VB, Grau T, Bernd A, Zrenner E, Jagle H, Renner AB, Kellner U, Rudolph G, Jacobson SG, Cideciyan AV, Schaich S, Kohl S, Wissinger B
ABCA4 gene analysis in patients with autosomal recessive cone and cone rod dystrophies.
Eur J Hum Genet. 2008 Jul;16(7):812-9. Epub 2008 Feb 20., [PMID:18285826]

Abstract [show]
The ATP-binding cassette (ABC) transporters constitute a family of large membrane proteins, which transport a variety of substrates across membranes. The ABCA4 protein is expressed in photoreceptors and possibly functions as a transporter for N-retinylidene-phosphatidylethanolamine (N-retinylidene-PE), the Schiff base adduct of all-trans-retinal with PE. Mutations in the ABCA4 gene have been initially associated with autosomal recessive Stargardt disease. Subsequent studies have shown that mutations in ABCA4 can also cause a variety of other retinal dystrophies including cone rod dystrophy and retinitis pigmentosa. To determine the prevalence and mutation spectrum of ABCA4 gene mutations in non-Stargardt phenotypes, we have screened 64 unrelated patients with autosomal recessive cone (arCD) and cone rod dystrophy (arCRD) applying the Asper Ophthalmics ABCR400 microarray followed by DNA sequencing of all coding exons of the ABCA4 gene in subjects with single heterozygous mutations. Disease-associated ABCA4 alleles were identified in 20 of 64 patients with arCD or arCRD. In four of 64 patients (6%) only one mutant ABCA4 allele was detected and in 16 patients (25%), mutations on both ABCA4 alleles were identified. Based on these data we estimate a prevalence of 31% for ABCA4 mutations in arCD and arCRD, supporting the concept that the ABCA4 gene is a major locus for various types of degenerative retinal diseases with abnormalities in cone or both cone and rod function.

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70 of alleles Reference Missense: 6 c.731T4Ca p.L244P 2 23 12 c.1622T4Cb p.L541P 1 5 13 c.1928T4G p.V643G 1 9 17 c.2588G4C p.G863A and p.G863del 2 4 21 c.3113C4Tb p.A1038V 1 4 25 c.3608G4A p.G1203E 1 24 28 c.4139C4T p.P1380L 2 25 30 c.4457C4T p.P1486L 1 25 30 c.4462T4C p.C1488R 1 25 37 c.5285C4A p.A1762D 1 24 41 c.5819T4C p.L1940P 1 26 42 c.5882G4A p.G1961E 1 9 45 c.6148G4C p.V2050L 1 25 45 c.6229C4T p.R2077W 1 25 Nonsense: 6 c.700C4T p.Q234X 1 This study 6 c.735T4G p.Y245X 2 24 28 c.4234C4T p.Q1412X 1 10 Deletion: 24 c.3539_3554del p.S1181PfsX8 1 This study 43 c.5917delG p.V1973X 3 27 Splice site/intronic: 26 c.5196+1G4A Splicing 1 9 34 c.4848+2T4C Splicing 1 This study 36 c.5196+1_5196+4del Splicing 1 15 39 c.5461À10T4C Unknown 8 14 40 c.5714+5G4A Splicing? Login to comment

[hide] Evidence of widespread retinal dysfunction in pati... Invest Ophthalmol Vis Sci. 2008 Mar;49(3):1191-9. Maia-Lopes S, Silva ED, Silva MF, Reis A, Faria P, Castelo-Branco M
Evidence of widespread retinal dysfunction in patients with stargardt disease and morphologically unaffected carrier relatives.
Invest Ophthalmol Vis Sci. 2008 Mar;49(3):1191-9., [PMID:18326749]

Abstract [show]
PURPOSE: To characterize contrast sensitivity (CS) across the visual field for two achromatic spatial-temporal frequencies in 21 families with Stargardt disease (STGD) and to correlate psychophysical impairment with patterns of change in multifocal electroretinography (mfERG). METHODS: Twenty-seven eyes from patients with STGD, 16 eyes from asymptomatic relatives, and 44 age-matched control eyes were included. Chromatic CS function was assessed by comparing protan, deutan, and tritan (Cambridge Color Test; Cambridge Research Systems Ltd., Rochester, UK) and anomaloscope measures (IF-2; Roland Consult, Wiesbaden, Germany). Achromatic CS measures were obtained with custom-made software in nine locations by using randomly interleaved staircases. The first task-low spatial frequency (LSF)-matched the known frequency-doubling method that is believed to activate the magnocellular pathway preferentially. The second included an intermediate spatial frequency (ISF, 3.5 cyc/deg). mfERGs (RETIscan; Roland Consult) were also obtained. Relatives were screened for ABCA4 mutations by ABCR400 microarray and direct sequencing. RESULTS: Central impairment of achromatic and chromatic CS (along the three isolation axes) was observed in STGD. LSF and ISF tasks revealed significant and widespread dysfunction in patients and their morphologically unaffected relatives, 80% of whom were found to be ABCA4 mutation carriers. Significant reduction of P1 amplitudes was also observed in both groups. CONCLUSIONS: CS function is impaired in patients with STGD at distinct spatial-temporal frequencies, which, in addition to the color vision deficits, suggests dual impairment of the magno- parvocellular pathways. STGD morphologically unaffected carriers may show patterns of psychophysical dysfunction that are mirrored by abnormal mfERG responses.

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150 Several other sequence changes that have been significantly correlated to the STGD phenotype (M1V, N96D, R290W, L2027F, R2030Q, V2050L, 3211insGT, and IVS40ϩ5GϾA) were also identified. Login to comment
134 Several other sequence changes that have been significantly correlated to the STGD phenotype (M1V, N96D, R290W, L2027F, R2030Q, V2050L, 3211insGT, and IVS40af9;5Gb0e;A) were also identified. Login to comment

[hide] Correlation of clinical and genetic findings in Hu... Invest Ophthalmol Vis Sci. 2005 Dec;46(12):4402-8. Hargitai J, Zernant J, Somfai GM, Vamos R, Farkas A, Salacz G, Allikmets R
Correlation of clinical and genetic findings in Hungarian patients with Stargardt disease.
Invest Ophthalmol Vis Sci. 2005 Dec;46(12):4402-8., [PMID:16303926]

Abstract [show]
PURPOSE: Autosomal recessive Stargardt disease (arSTGD) presents with substantial clinical and genetic heterogeneity. This study was conducted to correlate foveolar thickness (FT) and total macular volume (TMV), measured by optical coherence tomography (OCT), with other clinical characteristics and with specific genetic variation in Hungarian patients with arSTGD. METHODS: After a standard ophthalmic workup, both eyes of 35 patients with STGD from Hungary and of 25 age-matched healthy control subjects were tested with OCT. FT and TMV were measured automatically with the OCT mapping software in the nine Early Treatment Diabetic Retinopathy Study areas of 3500 microm in diameter. All patients were screened for mutations by a combination of the ABCR400 microarray and direct sequencing. RESULTS: The patients with STGD presented with markedly thinned retina in the foveola and decreased macular volume, 72 microm and 1.69 mm3, respectively, compared with 169 microm and 2.48 mm3 in the normal subjects, respectively. Statistically significant correlation was observed between visual acuity (VA) and TMV and between VA and FT. Disease-associated mutations were detected in 23 (65.7%) of 35 patients, including 48.5% with both alleles and 17.2% with one allele. The most frequent ABCA4 alleles in Hungarian patients with STGD were L541P/A1038V (in 28% of all patients), G1961E (20%) and IVS40+5G-->A (17%). Specific genotypes correlated with some phenotypic features and allowed for predictions of the disease progression. CONCLUSIONS: Hungarian patients with STGD presented with extensive foveolar thinning and macular volume loss. Genetic analysis detected several ABCA4 alleles at high frequency in the cohort of patients, suggesting founder effect(s). Unusually homogeneous distribution of disease-associated mutations aided genotype-phenotype correlation analyses in this population.

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89 Summarized Clinical and Genetic Data of Patients with STGD Patient Allele 1 Allele 2 Fishman OU Gender Age Duration VA OD VA OS FT OD (␮m) FT OS (␮m) MV OD (mm3 ) MV OS (mm3 ) 1 ND ND I M 18 10 0.42 0.50 90.00 76.00 1.70 1.67 2 L541P/A1038V ND III F 27 15 0.06 0.08 43.00 58.00 1.27 1.28 3 5917delG 5917delG II F 29 8 0.17 0.17 54.00 20.00 1.38 1.35 4 ND ND III F 42 14 0.10 0.10 91.00 71.00 1.60 1.59 5 V2050L ND II F 22 5 0.20 0.33 28.00 77.00 1.64 1.68 6 ND ND II F 17 2 1.00 0.71 156.00 141.00 2.55 2.6 7 IVS40ϩ5GϾA ND III M 28 13 0.10 0.06 71.00 92.00 1.61 1.61 8 L541P/A1038V G1961E II M 37 15 0.10 0.10 87.00 97.00 1.95 1.95 9 106delT G1961E II M 32 7 0.08 0.08 51.00 32.00 1.59 1.66 10 ND ND I F 55 17 0.25 0.56 160.00 170.00 1.72 1.82 11 L541P/A1038V G863A II F 15 3 0.25 0.33 67.00 68.00 1.78 1.76 12 IVS40ϩ5GϾA 5917delG III M 15 6 0.20 0.20 107.00 117.00 1.93 1.92 13 ND ND I M 27 2 0.38 0.33 56.00 86.00 2.01 1.97 14 G1886E G1961E II F 37 9 0.12 0.16 92.00 46.00 1.55 1.59 15 G1961E ND III F 20 5 0.30 0.20 49.00 34.00 1.43 1.53 16 ND ND II M 28 14 0.32 0.08 52.00 60.00 1.46 1.52 17 IVS40ϩ5GϾA 5917delG III M 27 5 0.10 0.10 97.00 92.00 1.76 1.71 18 L541P/A1038V D1532N III M 28 12 0.25 0.10 49.00 46.00 1.83 1.86 19 ND ND II F 31 11 0.10 0.13 67.00 72.00 1.55 1.49 20 L541P L541P/A1038V II F 15 5 0.10 0.10 28.00 34.00 1.63 1.65 21 L541P/A1038V G863A II F 25 2 0.20 0.62 94.00 81.00 1.92 1.94 22 L541P/A1038V ND II M 18 9 0.08 0.10 63.00 72.00 1.40 1.43 23 G1961E ND III F 34 9 0.16 0.16 16.00 23.00 1.31 1.56 24 ND ND II F 52 14 0.16 0.16 122.00 113.00 1.90 1.99 25 P68L L541P/A1038V III M 37 22 0.10 0.12 40.00 40.00 1.41 1.42 26 ND ND II F 18 11 0.20 0.25 59.00 72.00 1.42 1.47 27 L541P/A1038V G1961E II F 24 7 0.18 0.18 83.00 100.00 1.72 1.77 28 IVS40ϩ5GϾA 5917delG III M 15 7 0.10 0.16 38.00 46.00 1.30 1.41 29 R1108C R1108C II M 31 14 0.10 0.10 41.00 44.00 1.95 1.96 30 G1961E ND II M 28 6 0.33 0.56 91.00 129.00 1.98 2.04 31 ND ND II F 28 11 0.08 0.10 55.00 63.00 1.52 1.59 32 L541P/A1038V G863A II M 32 15 0.20 0.20 92.00 86.00 1.80 1.75 33 ND ND II F 27 4 0.25 0.20 66.00 75.00 1.72 1.76 34 ND ND II F 36 8 0.12 0.10 58.00 69.00 1.59 1.56 35 IVS40ϩ5GϾA IVS40ϩ5GϾA III F 19 6 0.10 0.10 62.00 53.00 1.67 1.65 Fishman OU, classification of patients by fundus photos in three categories according to Fishman et al.25 ND, not determined. Login to comment
87 Summarized Clinical and Genetic Data of Patients with STGD Patient Allele 1 Allele 2 Fishman OU Gender Age Duration VA OD VA OS FT OD (òe;m) FT OS (òe;m) MV OD (mm3 ) MV OS (mm3 ) 1 ND ND I M 18 10 0.42 0.50 90.00 76.00 1.70 1.67 2 L541P/A1038V ND III F 27 15 0.06 0.08 43.00 58.00 1.27 1.28 3 5917delG 5917delG II F 29 8 0.17 0.17 54.00 20.00 1.38 1.35 4 ND ND III F 42 14 0.10 0.10 91.00 71.00 1.60 1.59 5 V2050L ND II F 22 5 0.20 0.33 28.00 77.00 1.64 1.68 6 ND ND II F 17 2 1.00 0.71 156.00 141.00 2.55 2.6 7 IVS40af9;5Gb0e;A ND III M 28 13 0.10 0.06 71.00 92.00 1.61 1.61 8 L541P/A1038V G1961E II M 37 15 0.10 0.10 87.00 97.00 1.95 1.95 9 106delT G1961E II M 32 7 0.08 0.08 51.00 32.00 1.59 1.66 10 ND ND I F 55 17 0.25 0.56 160.00 170.00 1.72 1.82 11 L541P/A1038V G863A II F 15 3 0.25 0.33 67.00 68.00 1.78 1.76 12 IVS40af9;5Gb0e;A 5917delG III M 15 6 0.20 0.20 107.00 117.00 1.93 1.92 13 ND ND I M 27 2 0.38 0.33 56.00 86.00 2.01 1.97 14 G1886E G1961E II F 37 9 0.12 0.16 92.00 46.00 1.55 1.59 15 G1961E ND III F 20 5 0.30 0.20 49.00 34.00 1.43 1.53 16 ND ND II M 28 14 0.32 0.08 52.00 60.00 1.46 1.52 17 IVS40af9;5Gb0e;A 5917delG III M 27 5 0.10 0.10 97.00 92.00 1.76 1.71 18 L541P/A1038V D1532N III M 28 12 0.25 0.10 49.00 46.00 1.83 1.86 19 ND ND II F 31 11 0.10 0.13 67.00 72.00 1.55 1.49 20 L541P L541P/A1038V II F 15 5 0.10 0.10 28.00 34.00 1.63 1.65 21 L541P/A1038V G863A II F 25 2 0.20 0.62 94.00 81.00 1.92 1.94 22 L541P/A1038V ND II M 18 9 0.08 0.10 63.00 72.00 1.40 1.43 23 G1961E ND III F 34 9 0.16 0.16 16.00 23.00 1.31 1.56 24 ND ND II F 52 14 0.16 0.16 122.00 113.00 1.90 1.99 25 P68L L541P/A1038V III M 37 22 0.10 0.12 40.00 40.00 1.41 1.42 26 ND ND II F 18 11 0.20 0.25 59.00 72.00 1.42 1.47 27 L541P/A1038V G1961E II F 24 7 0.18 0.18 83.00 100.00 1.72 1.77 28 IVS40af9;5Gb0e;A 5917delG III M 15 7 0.10 0.16 38.00 46.00 1.30 1.41 29 R1108C R1108C II M 31 14 0.10 0.10 41.00 44.00 1.95 1.96 30 G1961E ND II M 28 6 0.33 0.56 91.00 129.00 1.98 2.04 31 ND ND II F 28 11 0.08 0.10 55.00 63.00 1.52 1.59 32 L541P/A1038V G863A II M 32 15 0.20 0.20 92.00 86.00 1.80 1.75 33 ND ND II F 27 4 0.25 0.20 66.00 75.00 1.72 1.76 34 ND ND II F 36 8 0.12 0.10 58.00 69.00 1.59 1.56 35 IVS40af9;5Gb0e;A IVS40af9;5Gb0e;A III F 19 6 0.10 0.10 62.00 53.00 1.67 1.65 Fishman OU, classification of patients by fundus photos in three categories according to Fishman et al.25 ND, not determined. Login to comment

[hide] ABCA4 mutations causing mislocalization are found ... Hum Mol Genet. 2005 Oct 1;14(19):2769-78. Epub 2005 Aug 15. Wiszniewski W, Zaremba CM, Yatsenko AN, Jamrich M, Wensel TG, Lewis RA, Lupski JR
ABCA4 mutations causing mislocalization are found frequently in patients with severe retinal dystrophies.
Hum Mol Genet. 2005 Oct 1;14(19):2769-78. Epub 2005 Aug 15., [PMID:16103129]

Abstract [show]
ABCA4, also called ABCR, is a retinal-specific member of the ATP-binding cassette (ABC) family that functions in photoreceptor outer segments as a flipase of all-trans retinal. Homozygous and compound heterozygous ABCA4 mutations are associated with various autosomal recessive retinal dystrophies, whereas heterozygous ABCA4 mutations have been associated with dominant susceptibility to age-related macular degeneration in both humans and mice. We analyzed a cohort of 29 arRP families for the mutations in ABCA4 with a commercial microarray, ABCR-400 in addition to direct sequencing and segregation analysis, and identified both mutant alleles in two families (7%): compound heterozygosity for missense (R602W) and nonsense (R408X) alleles and homozygosity for a complex [L541P; A1038V] allele. The missense mutations were analyzed functionally in the photoreceptors of Xenopus laevis tadpoles, which revealed mislocalization of ABCA4 protein. These mutations cause retention of ABCA4 in the photoreceptor inner segment, likely by impairing correct folding, resulting in the total absence of physiologic protein function. Patients with different retinal dystrophies harboring two misfolding alleles exhibit early age-of-onset (AO) (5-12 years) of retinal disease. Our data suggest that a class of ABCA4 mutants may be an important determinant of the AO of disease.

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39 arRP patients from five families (AR168, AR192, AR194, AR554 and AR591) were heterozygous for various missense ABCA4 mutations that by conceptual translation would lead to either an amino acid change (G1961E, V2050L and D2177 N) or splicing alteration (36IVSþ1G . Login to comment
44 A WT 168-05 24 20/25 OD; 20/30 OS;VF , 308 OU RP N/A N/A 168-06 26 N/A RP N/A N/A AR192 192-03 9 20/20 OD; 20/25 OS;VF , 58 OU RP D2177N WT 192-04 19 20/30 OD; 20/40 OS;VF , 58 OU RP WT WT 192-05 19 20/30 OD; 20/40 OS;VF , 58 OU RP WT WT AR194 194-03 30 N/A RP D2177N WT 194-05 Childhood 20/25 OD; 20/40 OS RP N/A N/A 194-06 5 N/A RP D2177N WT 194-07 4 or 5 20/80 OU RP N/A N/A AR197 197-05 7 CF 3 feet OD; CF 2 feet OS RP [L541P; A1038V] [L541P; A1038V] 197-06 9 CF 5 feet OD; HM OS RP [L541P; A1038V] [L541P; A1038V] AR554 554-03 2 10/12 20/60 OU RP V2050L WT 554-04 1 9/12 N/A RP N/A N/A AR591 591-03 20 20/25 OU RP N/A N/A 591-04 8 20/20 OD; 20/25 OS;VF , 108 OU RP G1961E WT AR689 689-03 7 N/A RP R408X R602W 689-08 7 N/A RP N/A N/A OD, right eye; OS, left eye; OU, both eyes; VF, visual field; RP, retinitis pigementosa, WT, wild type; N/A, not available; CF, counting fingers; HM, hand motions. Login to comment
131 In subjects from five RP families (9% of disease alleles), we found heterozygous missense ABCA4 mutations (G1961E, V2050L, D2177 N and 36IVSþ1) that are suggested to have functional consequences for ABCA4 activity (29,36). Login to comment

[hide] Age matters--thoughts on a grading system for ABCA... Graefes Arch Clin Exp Ophthalmol. 2005 Feb;243(2):87-9. Epub 2004 Dec 22. Lorenz B, Preising MN
Age matters--thoughts on a grading system for ABCA4 mutations.
Graefes Arch Clin Exp Ophthalmol. 2005 Feb;243(2):87-9. Epub 2004 Dec 22., [PMID:15614538]

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33 All carry mutations which have been reported mostly in AMD (D2177N, V2050L [1, 16, 18]) or STGD (L541P+A1038V [3]). Login to comment
34 All carry mutations which have been reported mostly in AMD (D2177N, V2050L [1, 16, 18]) or STGD (L541P+A1038V [3]). Login to comment

[hide] Microarray-based mutation analysis of the ABCA4 (A... Eur J Hum Genet. 2004 Dec;12(12):1024-32. Klevering BJ, Yzer S, Rohrschneider K, Zonneveld M, Allikmets R, van den Born LI, Maugeri A, Hoyng CB, Cremers FP
Microarray-based mutation analysis of the ABCA4 (ABCR) gene in autosomal recessive cone-rod dystrophy and retinitis pigmentosa.
Eur J Hum Genet. 2004 Dec;12(12):1024-32., [PMID:15494742]

Abstract [show]
Mutations in the ABCA4 gene have been associated with autosomal recessive Stargardt disease (STGD1), cone-rod dystrophy (CRD), and retinitis pigmentosa (RP). We employed a recently developed genotyping microarray, the ABCR400-chip, to search for known ABCA4 mutations in patients with isolated or autosomal recessive CRD (54 cases) or RP (90 cases). We performed detailed ophthalmologic examinations and identified at least one ABCA4 mutation in 18 patients (33%) with CRD and in five patients (5.6%) with RP. Single-strand conformation polymorphism (SSCP) analysis and subsequent DNA sequencing revealed four novel missense mutations (R24C, E161K, P597S, G618E) and a novel 1-bp deletion (5888delG). Ophthalmoscopic abnormalities in CRD patients ranged from minor granular pigmentary changes in the posterior pole to widespread atrophy. In 12 patients with recordable electroretinogram (ERG) tracings, a cone-rod pattern was detected. Three patients demonstrated progression from a retinal dystrophy resembling STGD1 to a more widespread degeneration, and were subsequently diagnosed as CRD. In addition to a variable degree of atrophy, all RP patients displayed ophthalmologic characteristics of classic RP. When detectable, ERG recordings in these patients demonstrated rod-cone patterns of photoreceptor degeneration. In conclusion, in this study, we show that the ABCA4 mutation chip is an efficient first screening tool for arCRD.

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101 Likewise, the known Table 2 ABCA4 sequence variants in RP patients RP patient number Inheritance Allele 1 Allele 2 Nucleotide change Effect Nucleotide change Effect 9304 Aut. Rec. 2588G4C; 2828G4Aa DG863/G863A; R943Q 5888delG R1963fs 9444 Aut. Rec. 6529G4A D2177N Not identified 9545 Isolated 6529G4A D2177N Not identified 14753 Isolated 1622T4C; 3113C4T L541P; A1038V Not identified 17597 Isolated 6148G4C V2050L Not identified a Polymorphic variants 4203A, 5603 T, and 5682C also present. Login to comment
114 For two conservative missense mutations (V1433I and V2050L), the pathologic nature can be questioned. Login to comment
143 Given this clinical presentation and the fact that homozygous null mutations were not found Table 5 Functional assessment of missense (A) and splice site (B) mutations (A) Missense mutation Nature of amino-acid change Effect on ABCR functionRef R18W Nonconservative Unknown R24C Nonconservative Unknown; adjacent to first transmembrane domain G65E Nonconservative Unknown E161K Nonconservative Unknown L541P Conservative Decreased ATP binding and ATPase activity50 P597S Nonconservative Unknown G618E Nonconservative Unknown V767D Nonconservative Decreased ABCR expression10 G863A Nonconservative Decreased ATPase activity50, 51 R943Q Nonconservative Decreased ATPase activity51 A1038V Conservative Decreased ATP binding and ATPase activity50 E1087K Nonconservative Decreased ATP binding50 V1433I Conservative Unknown R1640W Nonconservative Unknown A1794D Nonconservative Introduction charged aa in 10th transmembrane domain G1961E Nonconservative Decreased ATP binding and ATPase activity 50 V2050L Conservative Unknown D2177N Nonconservative Increased ATPase activity50 (B) Splice site mutation Effect on mRNARef Predicted effect on ABCR protein 768G4T Nonsense-mediated decay33 No protein IVS36+2T4C Unknown Truncation of exon 36 resulting in V1673fs? Login to comment

[hide] Denaturing HPLC profiling of the ABCA4 gene for re... Clin Chem. 2004 Aug;50(8):1336-43. Epub 2004 Jun 10. Stenirri S, Fermo I, Battistella S, Galbiati S, Soriani N, Paroni R, Manitto MP, Martina E, Brancato R, Allikmets R, Ferrari M, Cremonesi L
Denaturing HPLC profiling of the ABCA4 gene for reliable detection of allelic variations.
Clin Chem. 2004 Aug;50(8):1336-43. Epub 2004 Jun 10., [PMID:15192030]

Abstract [show]
BACKGROUND: Mutations in the retina-specific ABC transporter (ABCA4) gene have been associated with several forms of macular degenerations. Because the high complexity of the molecular genotype makes scanning of the ABCA4 gene cumbersome, we describe here the first use of denaturing HPLC (DHPLC) to screen for ABCA4 mutations. METHODS: Temperature conditions were designed for all 50 exons based on effective separation of 83 samples carrying 86 sequence variations and 19 mutagenized controls. For validation, samples from 23 previously characterized Stargardt patients were subjected to DHPLC profiling. Subsequently, samples from a cohort of 30 patients affected by various forms of macular degeneration were subjected to DHPLC scanning under the same conditions. RESULTS: DHPLC profiling not only identified all 132 sequence alterations previously detected by double-gradient denaturing gradient gel electrophoresis but also identified 5 sequence alterations that this approach had missed. Moreover, DHPLC scanning of an additional panel of 30 previously untested patients led to the identification of 26 different mutations and 29 polymorphisms, accounting for 203 sequence variations on 29 of the 30 patients screened. In total, the DHPLC approach allowed us to identify 16 mutations that had never been reported before. CONCLUSIONS: These results provide strong support for the use of DHPLC for molecular characterization of the ABCA4 gene.

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No. Sentence Comment
35 Exon Genotypesa Exon Genotypesa 1b M1V (1A>G) (11) 24 3523-28TϾC (12) R18W (52C>T) (11) 25 G1203D (3608G>A)b 3 250_251insCAAA (7) 27 R1300X (3898C>T) (12) N96K (288C>A) R1300Q (3899G>A) (11) 302 ϩ 26 GϾA (13) 28 P1380L (4139CϾT) (14) 4 P143L (428C>T) (10) P1401P (4203CϾA) (15) 5 R152Q (455G>A) (4) 4253 ϩ 43GϾA (12) 6 571-1GϾT (4) 29 4253 ϩ 13GϾA (12) R212H (635G>A) (16) 4354-38GϾA (4) C230S (688T>A) (12) 30a 4466 ϩ 3GϾA (4) 641delG (9) 30b C1490Y (4469G>A) (17) 10 1240-14CϾT (13) P1512R (4535C>G) (4) H423R (1268ϾG) (13) 31 T1526M (4577C>T) (14) 1357 ϩ 11delG (16) 33/34 A1598D (4793C>A) (4) H423H (1269CϾT) (13) 35 4947delC (14) 11 1387delTT (4) 5018 ؉ 2T>C (7) R500R (1500GϾA) (4) 39 H1838Y (5512C>T) (14) 12 L541P (1622T>C) (14) 40 N1868I (5603AϾT) (13) R572Q (1715G>A) (17) L1894L (5682GϾC) (15) 13 Y639X (1917C>G) (17) 5714 ؉ 5G>A C641S (1922G>C) (4) 41 L1938L (5814AϾG) (12) 14 R653C (1957C>T) (12) 42 5836-43CϾA W700X (2099G>A) (4) 5836-11GϾA (15) 3607 ϩ 49TϾC P1948I (5843CϾT) (15) 15 V767D (2300T>A) (7) P1948P (5844AϾG) (15) 16 W821R (2461T>A) (14) G1961E (5882G>A) (14) 17 2588-33CϾTb 43 L1970F (5908C>T) (11) G863A (2588G>C) (17) 44 6006-16AϾG (16) 18 2654-36CϾT (4) I2023I (6069CϾT) (14) T897I (2690C>T) (7) L2027F (6079C>T) (14) 19 R943Q (2828GϾA) (13) 45 V2050L (6148G>C) (14) Y954D (2860T>G) (4) 46 R2107H (6320G>A) (18) N965S (2894A>G) (14) 6386 ؉ 2G>C (10) 20 G978D (2933G>A) (4) 47 R2139W (6415C>T) (14) L988L (2964CϾT) (4) R2149L (6446G>T) (4) 21 E1022K (3064G>A) (4) C2150Y (6449G>A) (19) A1038V (3113C>T) (14) 48 D2177N (6529G>A) (17) G1050D (3149G>A) (4) L2241V (6721C>G) (12) 3211_3212insGT (14) 6729 ϩ 21CϾT (15) 22 E1087K (3259G>A) (14) 49 6730-3TϾC (15) R1098C (3292C>T) (12) S2255I (6764GϾT) (13) S1099P (3295T>C) (4) 6816 ϩ 28GϾC (4) R1108C (3322C>T) (14) R1129L (3386G>T) (17) a Bold indicates disease-causing mutations. Login to comment
34 Exon Genotypesa Exon Genotypesa 1b M1V (1A>G) (11) 24 3523-28Tb0e;C (12) R18W (52C>T) (11) 25 G1203D (3608G>A)b 3 250_251insCAAA (7) 27 R1300X (3898C>T) (12) N96K (288C>A) R1300Q (3899G>A) (11) 302 af9; 26 Gb0e;A (13) 28 P1380L (4139Cb0e;T) (14) 4 P143L (428C>T) (10) P1401P (4203Cb0e;A) (15) 5 R152Q (455G>A) (4) 4253 af9; 43Gb0e;A (12) 6 571-1Gb0e;T (4) 29 4253 af9; 13Gb0e;A (12) R212H (635G>A) (16) 4354-38Gb0e;A (4) C230S (688T>A) (12) 30a 4466 af9; 3Gb0e;A (4) 641delG (9) 30b C1490Y (4469G>A) (17) 10 1240-14Cb0e;T (13) P1512R (4535C>G) (4) H423R (1268b0e;G) (13) 31 T1526M (4577C>T) (14) 1357 af9; 11delG (16) 33/34 A1598D (4793C>A) (4) H423H (1269Cb0e;T) (13) 35 4947delC (14) 11 1387delTT (4) 5018 d19; 2T>C (7) R500R (1500Gb0e;A) (4) 39 H1838Y (5512C>T) (14) 12 L541P (1622T>C) (14) 40 N1868I (5603Ab0e;T) (13) R572Q (1715G>A) (17) L1894L (5682Gb0e;C) (15) 13 Y639X (1917C>G) (17) 5714 d19; 5G>A C641S (1922G>C) (4) 41 L1938L (5814Ab0e;G) (12) 14 R653C (1957C>T) (12) 42 5836-43Cb0e;A W700X (2099G>A) (4) 5836-11Gb0e;A (15) 3607 af9; 49Tb0e;C P1948I (5843Cb0e;T) (15) 15 V767D (2300T>A) (7) P1948P (5844Ab0e;G) (15) 16 W821R (2461T>A) (14) G1961E (5882G>A) (14) 17 2588-33Cb0e;Tb 43 L1970F (5908C>T) (11) G863A (2588G>C) (17) 44 6006-16Ab0e;G (16) 18 2654-36Cb0e;T (4) I2023I (6069Cb0e;T) (14) T897I (2690C>T) (7) L2027F (6079C>T) (14) 19 R943Q (2828Gb0e;A) (13) 45 V2050L (6148G>C) (14) Y954D (2860T>G) (4) 46 R2107H (6320G>A) (18) N965S (2894A>G) (14) 6386 d19; 2G>C (10) 20 G978D (2933G>A) (4) 47 R2139W (6415C>T) (14) L988L (2964Cb0e;T) (4) R2149L (6446G>T) (4) 21 E1022K (3064G>A) (4) C2150Y (6449G>A) (19) A1038V (3113C>T) (14) 48 D2177N (6529G>A) (17) G1050D (3149G>A) (4) L2241V (6721C>G) (12) 3211_3212insGT (14) 6729 af9; 21Cb0e;T (15) 22 E1087K (3259G>A) (14) 49 6730-3Tb0e;C (15) R1098C (3292C>T) (12) S2255I (6764Gb0e;T) (13) S1099P (3295T>C) (4) 6816 af9; 28Gb0e;C (4) R1108C (3322C>T) (14) R1129L (3386G>T) (17) a Bold indicates disease-causing mutations. Login to comment

[hide] ABCA4 gene sequence variations in patients with au... Arch Ophthalmol. 2003 Jun;121(6):851-5. Fishman GA, Stone EM, Eliason DA, Taylor CM, Lindeman M, Derlacki DJ
ABCA4 gene sequence variations in patients with autosomal recessive cone-rod dystrophy.
Arch Ophthalmol. 2003 Jun;121(6):851-5., [PMID:12796258]

Abstract [show]
OBJECTIVE: To identify sequence variations in the ABCA4 gene in a cohort of patients with autosomal recessive cone-rod dystrophy. METHODS: The coding sequences of the ABCA4 gene were analyzed in 30 unrelated probands. In those patients with plausible disease-causing variations, correlations were made between genotype and fundus phenotype as well as with electrophysiological and visual field findings. RESULTS: Sixteen (53%) of 30 probands were found to harbor plausible disease-causing variations in the ABCA4 gene. Two distinctly different fundus phenotypes were observed in our cohort of patients. Twelve patients showed diffuse pigmentary degenerative changes, whereas 4 showed either no pigmentary changes or only a mild degree of peripheral pigment degeneration. An associa-tion between certain sequence variations and each of these 2 different phenotypes was observed. CONCLUSIONS: Our findings confirm that a substantial percentage of patients with autosomal recessive cone-rod dystrophy are likely to harbor a mutation in the ABCA4 gene as the cause of their disease. The fundus phenotype observed in such patients is quite variable, and certain fundus phenotypes may be more associated with certain genotypes. Clinical Relevance Identification of the molecular genetic basis for various inherited human retinal dystrophies, such as cone-rod dystrophy, facilitates a potentially better understanding of the mechanisms by which photoreceptor cells degenerate. This in turn provides guidance as to how to better proceed in identifying the most optimal future therapeutic strategies.

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94 Patients With Cone-Rod Dystrophy Patient No./ Age, y/Sex Race/ Ethnicity Visual Acuity Visual Field Fundus Type* Mutation Cone vs Rod ERG ReductionOD OS 1/74/F AA 20/60 - 2 5/600 Central and peripheral loss 1 Gly1448Arg C = R 2/35/F W 10/350 5/400 Central and peripheral loss 1 Ala1038Val Leu541Pro C = R 3/42/F H 20/400 20/400 Central and peripheral loss 1 Ala1038Val Trp1618stop C = R 4/54/F W 10/180 10/140 Central scotoma 1 Donor splice, 5bp3Ј g-a intron 40 C = R 5/36/F W 10/120 10/60 - 1 Central scotoma 1 Leu541Pro Asp600Tyr C ↓ R 6/49/F W 5/160 5/180 Central and peripheral loss 1 Donor splice 5bp3Ј g-a intron 40 C = R 7/49/F W 10/350 4/350 Central and peripheral loss 1 Glu328Stop Val767Asp C = R 8/40/M W 10/225 20/400 Central and peripheral loss 1 Ala1038Val C = R 9/36/M W 5/600 5/350 Central and peripheral loss 1 Gly550Arg C = R 10/39/F AA 20/100 - 2 20/400 Central scotoma 1 Ala1038Val C = R 11/26/F W 20/200 20/200 Central and peripheral loss 1 Val2050Leu C ↓ R 12/36/M W 20/200 20/80+1 Central scotoma 1 Donor splice 5bp3Ј g-a intron 40 C = R 13/43/M AA 20/400 20/200 Central and peripheral loss 2 Leu1201Arg C = R (ND) 14/33/M P 20/40+1 20/50 Central scotoma 2 Leu2027Phe C ↓ R 15/44/M AA CF 20/400 Central and peripheral loss 2 Leu1201Arg C = R (ND) 16/56/M AA 20/40 20/40 Central scotoma 2 Leu2027Phe C = R Abbreviations: AA, African American; C ↓ R, cone responses more reduced than rod amplitudes; C = R, cone and rod amplitudes were similarly reduced; CF, counting fingers; ERG, electroretinogram; H, Hispanic; ND, nondetectable; P, Palestinian; W, white. Login to comment

[hide] Cosegregation and functional analysis of mutant AB... Hum Mol Genet. 2001 Nov 1;10(23):2671-8. Shroyer NF, Lewis RA, Yatsenko AN, Wensel TG, Lupski JR
Cosegregation and functional analysis of mutant ABCR (ABCA4) alleles in families that manifest both Stargardt disease and age-related macular degeneration.
Hum Mol Genet. 2001 Nov 1;10(23):2671-8., [PMID:11726554]

Abstract [show]
Mutations in ABCR (ABCA4) have been reported to cause a spectrum of autosomal recessively inherited retinopathies, including Stargardt disease (STGD), cone-rod dystrophy and retinitis pigmentosa. Individuals heterozygous for ABCR mutations may be predisposed to develop the multifactorial disorder age-related macular degeneration (AMD). We hypothesized that some carriers of STGD alleles have an increased risk to develop AMD. We tested this hypothesis in a cohort of families that manifest both STGD and AMD. With a direct-sequencing mutation detection strategy, we found that AMD-affected relatives of STGD patients are more likely to be carriers of pathogenic STGD alleles than predicted based on chance alone. We further investigated the role of AMD-associated ABCR mutations by testing for expression and ATP-binding defects in an in vitro biochemical assay. We found that mutations associated with AMD have a range of assayable defects ranging from no detectable defect to apparent null alleles. Of the 21 missense ABCR mutations reported in patients with AMD, 16 (76%) show abnormalities in protein expression, ATP-binding or ATPase activity. We infer that carrier relatives of STGD patients are predisposed to develop AMD.

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46 The complex allele [H1406Y; V2050L] was identified in STGD-affected AR215-4 (Fig. 1). Login to comment
97 Pedigree Maternal allele Paternal allele AMD relative A priori Cosegregation AR19 pGM, -6 0.5 - AR33 [W1408R; R1640W] R24H and D1532N mA, -16 0.5 Yes AR59 4232insTATG C1488R pGM, -6 0.5 No AR80 T1526M pGF, -5 0.5 - AR80 T1526M mGF, -7 0.5 Yes AR125 4947delC C1488R pGM, -7 0.5 Yes AR215 [H1406Y; V2050L] pGM, -5 0.5 - AR218 2160+1G→C G1961E mA, -8 0.5 No AR262 W821R pGGF, -7 0.25 No AR271 P68R E1087K mGA, -6 0.25 No AR335 D645N F608I mGM, -9 0.5 Yes AR382 R1108C mGM, -6 0.5 Yes AR389 E2096K 5714+5G→A pGM, -8 0.5 Yes AR397 5196+1G→A 5585-1G→A mA, -5 0.5 No AR410 A1038V 768G→T pC, -5 0.25 Yes AR422 pGM, -6 0.5 - AR423 P1380L D1532N pGF, -4 0.5 No AR468 P1380L P1380L mU, -9 0.5 Yes AR484 L2027F G550R mGU, -5 0.25 Yes AR562 R2107H 3050+5G→A pGU, -5 0.25 No AR643 5196+2T→C L2027F mU, -4 0.5 Yes AR661 P1380L C54Y mGF, -6 0.5 Yes AR669 664del13 pGF, -4 0.5 No AR534 W821R P1380L pGM, -7 0.5 Yes (17) Family 1 R212C I2113M mGM, I-2 0.5 Yes (27) Family 2 R1108C R2107H mGM, I-2 0.5 Yes (27) Family 3 R212C G1977S mGF, I-1 0.5 Yes (27) 10.25 15 unlikely to account for many of the remaining alleles (our unpublished observations). Login to comment

[hide] Mutational scanning of the ABCR gene with double-g... Hum Genet. 2001 Sep;109(3):326-38. Fumagalli A, Ferrari M, Soriani N, Gessi A, Foglieni B, Martina E, Manitto MP, Brancato R, Dean M, Allikmets R, Cremonesi L
Mutational scanning of the ABCR gene with double-gradient denaturing-gradient gel electrophoresis (DG-DGGE) in Italian Stargardt disease patients.
Hum Genet. 2001 Sep;109(3):326-38., [PMID:11702214]

Abstract [show]
Mutations in the retina-specific ABC transporter (ABCR) gene are responsible for autosomal recessive Stargardt disease (arSTGD). Mutation detection efficiency in ABCR in arSTGD patients ranges between 30% and 66% in previously published studies, because of high allelic heterogeneity and technical limitations of the employed methods. Conditions were developed to screen the ABCR gene by double-gradient denaturing-gradient gel electrophoresis. The efficacy of this method was evaluated by analysis of DNA samples with previously characterized ABCR mutations. This approach was applied to mutation detection in 44 Italian arSTGD patients corresponding to 36 independent genomes, in order to assess the nature and frequency of the ABCR mutations in this ethnic group. In 34 of 36 (94.4%) STGD patients, 37 sequence changes were identified, including 26 missense, six frameshift, three splicing, and two nonsense variations. Among these, 20 had not been previously described. Several polymorphisms were detected in affected individuals and in matched controls. Our findings extend the spectrum of mutations identified in STGD patients and suggest the existence of a subset of molecular defects specific to the Italian population. The identification of at least two disease-associated mutations in four healthy control individuals indicates a higher than expected carrier frequency of variant ABCR alleles in the general population. Genotype-phenotype analysis in our series showed a possible correlation between the nature and location of some mutations and specific ophthalmoscopic features of STGD disease.

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37 DNA samples (n=22) carrying previously identified mutations in the ABCR gene were employed as controls for evaluating the efficacy of the DG-DGGE approach in detecting sequence variations R572Q (Lewis et al. 1999), Y639X (Lewis et al. 1999), G863A (Lewis et al. 1999; Maugeri et al. 1999), A1038V (Rozet et al. 1998), T1019M (Rozet et al. 1998), 3211insGT (Lewis et al. 1999), P1380L (Lewis et al. 1999), H1406Y (Lewis et al. 1999), 4947delC (Lewis et al. 1999), H1838Y (Lewis et al. 1999), 5714+5G→A (Cremers et al. 1998), N1868I (De La Paz et al. 1999), L1938L (Rivera et al. 2000), G1961E (Allikmets et al. 1997a, 1997b), L1970F (Lewis et al. 1999), L2027F (Nasonkin et al. 1998), V2050L (Lewis et al. 1999), E2131K (Lewis et al. 1999), R2139W (Lewis et al. 1999), 6709insG (Lewis et al. 1999), D2177N (Allikmets et al. 1997a, 1997b), 2181del12 (Lewis et al. 1999). Login to comment

[hide] Mutations in ABCR (ABCA4) in patients with Stargar... Invest Ophthalmol Vis Sci. 2001 Sep;42(10):2229-36. Briggs CE, Rucinski D, Rosenfeld PJ, Hirose T, Berson EL, Dryja TP
Mutations in ABCR (ABCA4) in patients with Stargardt macular degeneration or cone-rod degeneration.
Invest Ophthalmol Vis Sci. 2001 Sep;42(10):2229-36., [PMID:11527935]

Abstract [show]
PURPOSE: To determine the spectrum of ABCR mutations associated with Stargardt macular degeneration and cone-rod degeneration (CRD). METHODS: One hundred eighteen unrelated patients with recessive Stargardt macular degeneration and eight with recessive CRD were screened for mutations in ABCR (ABCA4) by single-strand conformation polymorphism analysis. Variants were characterized by direct genomic sequencing. Segregation analysis was performed on the families of 20 patients in whom at least two or more likely pathogenic sequence changes were identified. RESULTS: The authors found 77 sequence changes likely to be pathogenic: 21 null mutations (15 novel), 55 missense changes (26 novel), and one deletion of a consensus glycosylation site (also novel). Fifty-two patients with Stargardt macular degeneration (44% of those screened) and five with CRD each had two of these sequence changes or were homozygous for one of them. Segregation analyses in the families of 19 of these patients were informative and revealed that the index cases and all available affected siblings were compound heterozygotes or homozygotes. The authors found one instance of an apparently de novo mutation, Ile824Thr, in a patient. Thirty-seven (31%) of the 118 patients with Stargardt disease and one with CRD had only one likely pathogenic sequence change. Twenty-nine patients with Stargardt disease (25%) and two with CRD had no identified sequence changes. CONCLUSIONS: This report of 42 novel mutations brings the growing number of identified likely pathogenic sequence changes in ABCR to approximately 250.

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147 Missense Changes Found in Patients with No Other Detected ABCR Changes Patient ID Missense Change Mouse abc134 Mouse abc234 Human ABCC35 032-069 Ala60Val Ala N/A Glu 032-028 Gly65Glu Gly N/A Leu 032-044 Gly550Arg* Gly N/A N/A 032-038 Trp821Arg‡ Trp N/A Trp 035-019, 032-097 Glu1122Lys Glu Glu Glu 032-063, 032-093 Arg2030Gln† Arg Arg Arg 071-002 Leu2035Pro Phe Leu Met 032-064 Val2050Leu Phe Val Cys 032-061 Arg2107His Arg Arg Arg 007-009 Gly2146Asp‡ Gly Gly Gly Residues at homologous locations in other ABCR proteins. Login to comment
144 Missense Changes Found in Patients with No Other Detected ABCR Changes Patient ID Missense Change Mouse abc134 Mouse abc234 Human ABCC35 032-069 Ala60Val Ala N/A Glu 032-028 Gly65Glu Gly N/A Leu 032-044 Gly550Arg* Gly N/A N/A 032-038 Trp821Argߥ Trp N/A Trp 035-019, 032-097 Glu1122Lys Glu Glu Glu 032-063, 032-093 Arg2030Glnߤ Arg Arg Arg 071-002 Leu2035Pro Phe Leu Met 032-064 Val2050Leu Phe Val Cys 032-061 Arg2107His Arg Arg Arg 007-009 Gly2146Aspߥ Gly Gly Gly Residues at homologous locations in other ABCR proteins. Login to comment

[hide] An analysis of allelic variation in the ABCA4 gene... Invest Ophthalmol Vis Sci. 2001 May;42(6):1179-89. Webster AR, Heon E, Lotery AJ, Vandenburgh K, Casavant TL, Oh KT, Beck G, Fishman GA, Lam BL, Levin A, Heckenlively JR, Jacobson SG, Weleber RG, Sheffield VC, Stone EM
An analysis of allelic variation in the ABCA4 gene.
Invest Ophthalmol Vis Sci. 2001 May;42(6):1179-89., [PMID:11328725]

Abstract [show]
PURPOSE: To assess the allelic variation of the ATP-binding transporter protein (ABCA4). METHODS: A combination of single-strand conformation polymorphism (SSCP) and automated DNA sequencing was used to systematically screen this gene for sequence variations in 374 unrelated probands with a clinical diagnosis of Stargardt disease, 182 patients with age-related macular degeneration (AMD), and 96 normal subjects. RESULTS: There was no significant difference in the proportion of any single variant or class of variant between the control and AMD groups. In contrast, truncating variants, amino acid substitutions, synonymous codon changes, and intronic variants were significantly enriched in patients with Stargardt disease when compared with their presence in subjects without Stargardt disease (Kruskal-Wallis P < 0.0001 for each variant group). Overall, there were 2480 instances of 213 different variants in the ABCA4 gene, including 589 instances of 97 amino acid substitutions, and 45 instances of 33 truncating variants. CONCLUSIONS: Of the 97 amino acid substitutions, 11 occurred at a frequency that made them unlikely to be high-penetrance recessive disease-causing variants (HPRDCV). After accounting for variants in cis, one or more changes that were compatible with HPRDCV were found on 35% of all Stargardt-associated alleles overall. The nucleotide diversity of the ABCA4 coding region, a collective measure of the number and prevalence of polymorphic sites in a region of DNA, was found to be 1.28, a value that is 9 to 400 times greater than that of two other macular disease genes that were examined in a similar fashion (VMD2 and EFEMP1).

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102 Thirty-Three Truncated and 98 Amino Acid-Changing Variants in the ABCA4 Gene Exon Nucleotide Change Effect (A) (B) AMD (n ‫؍‬ 182) Control (n ‫؍‬ 96) STGD (n ‫؍‬ 374) Allele Prevalence 2 106delT FS NS 0 0 1 Ͻ0.01 2 160 ϩ 1g 3 a Splice site NS 0 0 1 Ͻ0.01 3 161G 3 A Cys54Tyr NS 0 0 6 Ͻ0.01 3 179C 3 T Ala60Val NS 0 0 2 Ͻ0.01 3 194G 3 A Gly65Glu NS 0 0 2 Ͻ0.01 3 223T 3 G Cys75Gly NS 0 0 2 Ͻ0.01 3 247delCAAA FS NS 0 0 2 Ͻ0.01 3 298C 3 T Ser100Pro NS 0 0 1 Ͻ0.01 5 454C 3 T Arg152Stop NS 0 0 2 Ͻ0.01 6 574G 3 A Ala192Thr NS 0 0 1 Ͻ0.01 6 618C 3 G Ser206Arg NS 0 0 3 Ͻ0.01 6 634C 3 T Arg212Cys 0.02 Yes 0 0 7 0.01 6 635G 3 A Arg212His NS 2 2 6 0.01 6 658C 3 T Arg220Cys NS 0 0 2 Ͻ0.01 6 661delG FS NS 0 0 1 Ͻ0.01 666delAAAGACGGTGC 6 GC FS NS 0 0 1 Ͻ0.01 6 746A 3 C Asp249Gly NS 0 0 1 Ͻ0.01 8 899C 3 A Thr300Asn NS 0 0 1 Ͻ0.01 8 997C 3 T Arg333Trp NS 0 0 1 Ͻ0.01 9 1140T 3 A Asn380Lys NS 0 0 1 Ͻ0.01 9 1222C 3 T Arg408Stop NS 0 0 1 Ͻ0.01 10 1268A 3 G His423Arg NS 1 0 7 0.01 10 1335C 3 G Ser445Arg NS 0 0 1 Ͻ0.01 10 1344delG FS NS 0 0 1 Ͻ0.01 11 1411G 3 A Glu471Lys NS 0 0 3 Ͻ0.01 11 1513delATCAC FS NS 0 0 1 Ͻ0.01 12 1622T 3 C Leu541Pro 0.001 Yes 0 0 11 0.01 13 1804C 3 T Arg602Trp NS 0 0 3 Ͻ0.01 13 1805G 3 A Arg602Gln NS 0 0 1 Ͻ0.01 13 1819G 3 T Gly607Trp NS 0 0 1 Ͻ0.01 13 1823T 3 A Phe608Ile NS 0 0 1 Ͻ0.01 13 1927G 3 A Val643Met NS 0 0 1 Ͻ0.01 14 1989G 3 T Trp663Stop NS 0 0 1 Ͻ0.01 14 2005delAT FS NS 0 0 3 Ͻ0.01 14 2041C 3 T Arg681Stop NS 0 0 2 Ͻ0.01 14 2147C 3 T Thr716Met NS 0 0 1 Ͻ0.01 15 2291G 3 A Cys764Tyr NS 0 0 1 Ͻ0.01 15 2294G 3 A Ser765Asn NS 0 0 1 Ͻ0.01 15 2300T 3 A Val767Asp NS 0 0 2 Ͻ0.01 16 2385del16bp FS NS 0 0 1 Ͻ0.01 16 2453G 3 A Gly818Glu NS 0 0 1 Ͻ0.01 16 2461T 3 A Trp821Arg NS 0 0 1 Ͻ0.01 16 2546T 3 C Val849Ala NS 0 0 4 Ͻ0.01 16 2552G 3 A Gly851Asp NS 0 0 1 Ͻ0.01 16 2560G 3 A Ala854Thr NS 0 0 1 Ͻ0.01 17 2588G 3 C Gly863Ala 0.0006 No 2 2 28 0.02 17 2617T 3 C Phe873Leu NS 0 0 1 Ͻ0.01 18 2690C 3 T Thr897Ile NS 0 0 1 Ͻ0.01 18 2701A 3 G Thr901Ala NS 0 1 0 Ͻ0.01 18 2703A 3 G Thr901Arg NS 0 0 2 Ͻ0.01 19 2828G 3 A Arg943Gln NS 20 13 37 0.05 19 2883delC FS NS 0 0 1 Ͻ0.01 20 2894A 3 G Asn965Ser NS 0 0 3 Ͻ0.01 19 2912C 3 A Thr971Asn NS 0 0 1 Ͻ0.01 19 2915C 3 A Thr972Asn NS 0 0 1 Ͻ0.01 20 2920T 3 C Ser974Pro NS 0 0 1 Ͻ0.01 20 2966T 3 C Val989Ala NS 0 0 2 Ͻ0.01 20 2977del8bp FS NS 0 0 1 Ͻ0.01 20 3041T 3 G Leu1014Arg NS 0 0 1 Ͻ0.01 21 3055A 3 G Thr1019Ala NS 0 0 1 Ͻ0.01 21 3064G 3 A Glu1022Lys NS 0 0 1 Ͻ0.01 21 3091A 3 G Lys1031Glu NS 0 0 1 Ͻ0.01 21 3113G 3 T Ala1038Val 0.001 Yes 1 0 17 0.01 22 3205insAA FS NS 0 0 1 Ͻ0.01 22 3261G 3 A Glu1087Lys NS 0 0 2 Ͻ0.01 22 3322C 3 T Arg1108Cys 0.04 Yes 0 0 6 Ͻ0.01 22 3323G 3 A Arg1108His NS 0 0 1 Ͻ0.01 23 3364G 3 A Glu1122Lys NS 0 0 1 Ͻ0.01 (continues) Exon Nucleotide Change Effect (A) (B) AMD (n ‫؍‬ 182) Control (n ‫؍‬ 96) STGD (n ‫؍‬ 374) Allele Prevalence 23 3386G 3 T Arg1129Leu NS 0 0 3 Ͻ0.01 24 3531C 3 A Cys1158Stop NS 0 0 1 Ͻ0.01 25 3749T 3 C Leu1250Pro NS 0 0 1 Ͻ0.01 26 3835delGATTCT FS NS 0 0 1 Ͻ0.01 27 3940C 3 A Pro1314Thr NS 0 1 0 Ͻ0.01 28 4139C 3 T Pro1380Leu 0.001 Yes 0 0 10 0.01 28 4222T 3 C Trp1408Arg NS 0 0 2 Ͻ0.01 28 4223G 3 T Trp1408Leu NS 0 0 2 Ͻ0.01 28 4234C 3 T Gln1412stop NS 0 0 1 Ͻ0.01 29 4297G 3 A Val1433Ile NS 1 0 0 Ͻ0.01 29 4319T 3 C Phe1440Ser NS 0 0 1 Ͻ0.01 30 4353 - 1g 3 t Splice site NS 0 0 1 Ͻ0.01 30 4457C 3 T Pro1486Leu NS 0 0 1 Ͻ0.01 30 4462T 3 C Cys1488Arg NS 0 0 3 Ͻ0.01 30 4463G 3 T Cys1488Phe NS 0 0 2 Ͻ0.01 30 4469G 3 A Cys1490Tyr NS 0 0 3 Ͻ0.01 30 4531insC FS NS 0 0 2 Ͻ0.01 32 4538A 3 G Gln1513Arg NS 0 0 1 Ͻ0.01 30 4539 ϩ 1g 3 t Splice site NS 0 0 1 Ͻ0.01 31 4574T 3 C Leu1525Pro NS 0 0 1 Ͻ0.01 33 4733delGTTT FS NS 0 0 1 Ͻ0.01 4859delATAACAinsTCC 35 T FS NS 0 0 1 Ͻ0.01 36 4909G 3 A Ala1637Thr NS 0 0 1 Ͻ0.01 35 4918C 3 T Arg1640Trp NS 0 0 1 Ͻ0.01 35 4919G 3 A Arg1640Gln NS 0 0 1 Ͻ0.01 35 4954T 3 G Tyr1652Asp NS 0 0 1 Ͻ0.01 36 5077G 3 A Val1693Ile NS 0 0 1 Ͻ0.01 36 5186T 3 C Leu1729Pro NS 0 0 2 Ͻ0.01 36 5206T 3 C Ser1736Pro NS 0 0 1 Ͻ0.01 36 5212del11bp FS NS 0 0 1 Ͻ0.01 37 5225delTGGTGGTGGGC FS NS 0 0 1 Ͻ0.01 del LPA 37 5278del9bp 1760 NS 0 0 1 Ͻ0.01 37 5288delG FS NS 0 0 1 Ͻ0.01 38 5395A 3 G Asn1799Asp NS 0 0 1 Ͻ0.01 38 5451T 3 G Asp1817Glu NS 1 0 4 Ͻ0.01 39 5584 ϩ 5g 3 a Splice site 0.02 Yes 0 0 6 Ͻ0.01 40 5603A 3 T Asn1868Ile 0.0006 No 20 7 79 0.08 40 5651T 3 A Val1884GLu NS 0 0 1 Ͻ0.01 40 5657G 3 A Gly1886Glu NS 0 0 1 Ͻ0.01 40 5687T 3 A Val1896Asp NS 0 0 1 Ͻ0.01 40 5693G 3 A Arg1898His NS 0 0 1 Ͻ0.01 40 5714 ϩ 5g 3 a Splice site NS 0 0 1 Ͻ0.01 42 5843CA 3 TG Pro1948Leu NS 11 7 28 0.04 42 5882G 3 A Gly1961Glu Ͻ0.0001 Yes 1 0 43 0.03 43 5908C 3 T Leu1970Phe NS 1 0 1 Ͻ0.01 43 5917delG FS NS 0 0 1 Ͻ0.01 44 6079C 3 T Leu2027Phe 0.01 Yes 0 0 9 0.01 44 6088C 3 T Arg2030Stop NS 0 0 2 Ͻ0.01 44 6089G 3 A Arg2030Gln NS 0 0 1 Ͻ0.01 44 6112A 3 T Arg2038Trp NS 0 0 1 Ͻ0.01 45 6148A 3 C Val2050Leu NS 1 0 0 Ͻ0.01 46 6212A 3 T Tyr2071Phe NS 0 0 1 Ͻ0.01 45 6229C 3 T Arg2077Trp NS 0 0 2 Ͻ0.01 46 6320G 3 A Arg2107His 0.01 Yes 0 0 10 0.01 46 6383A 3 G His2128Arg NS 0 0 1 Ͻ0.01 47 6446G 3 T Arg2149Leu NS 0 0 1 Ͻ0.01 47 6449G 3 A Cys2150Tyr NS 0 0 5 Ͻ0.01 48 6529G 3 A Asp2177Asn NS 2 0 0 Ͻ0.01 48 6686T 3 C Leu2229Pro NS 0 0 1 Ͻ0.01 48 6707delTCACACAG FS NS 0 0 1 Ͻ0.01 48 6729 ϩ 1g 3 a Splice site NS 0 0 1 Ͻ0.01 49 6764G 3 T Ser2255Ile 0.009 No 16 4 54 0.06 49 6788G 3 T Arg2263Leu NS 0 0 1 Ͻ0.01 (A) The probability under the null hypothesis of similar prevalence of each variant in Stargardt (STGD) compared with non-STGD alleles (two-tailed Fisher`s exact test); (B) compatability of the variant existing in a ratio of 100:1 in STGD to control alleles, calculated using the binomial distribution. 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103 Thirty-Three Truncated and 98 Amino Acid-Changing Variants in the ABCA4 Gene Exon Nucleotide Change Effect (A) (B) AMD (n d1d; 182) Control (n d1d; 96) STGD (n d1d; 374) Allele Prevalence 2 106delT FS NS 0 0 1 b0d;0.01 2 160 af9; 1g 3 a Splice site NS 0 0 1 b0d;0.01 3 161G 3 A Cys54Tyr NS 0 0 6 b0d;0.01 3 179C 3 T Ala60Val NS 0 0 2 b0d;0.01 3 194G 3 A Gly65Glu NS 0 0 2 b0d;0.01 3 223T 3 G Cys75Gly NS 0 0 2 b0d;0.01 3 247delCAAA FS NS 0 0 2 b0d;0.01 3 298C 3 T Ser100Pro NS 0 0 1 b0d;0.01 5 454C 3 T Arg152Stop NS 0 0 2 b0d;0.01 6 574G 3 A Ala192Thr NS 0 0 1 b0d;0.01 6 618C 3 G Ser206Arg NS 0 0 3 b0d;0.01 6 634C 3 T Arg212Cys 0.02 Yes 0 0 7 0.01 6 635G 3 A Arg212His NS 2 2 6 0.01 6 658C 3 T Arg220Cys NS 0 0 2 b0d;0.01 6 661delG FS NS 0 0 1 b0d;0.01 666delAAAGACGGTGC 6 GC FS NS 0 0 1 b0d;0.01 6 746A 3 C Asp249Gly NS 0 0 1 b0d;0.01 8 899C 3 A Thr300Asn NS 0 0 1 b0d;0.01 8 997C 3 T Arg333Trp NS 0 0 1 b0d;0.01 9 1140T 3 A Asn380Lys NS 0 0 1 b0d;0.01 9 1222C 3 T Arg408Stop NS 0 0 1 b0d;0.01 10 1268A 3 G His423Arg NS 1 0 7 0.01 10 1335C 3 G Ser445Arg NS 0 0 1 b0d;0.01 10 1344delG FS NS 0 0 1 b0d;0.01 11 1411G 3 A Glu471Lys NS 0 0 3 b0d;0.01 11 1513delATCAC FS NS 0 0 1 b0d;0.01 12 1622T 3 C Leu541Pro 0.001 Yes 0 0 11 0.01 13 1804C 3 T Arg602Trp NS 0 0 3 b0d;0.01 13 1805G 3 A Arg602Gln NS 0 0 1 b0d;0.01 13 1819G 3 T Gly607Trp NS 0 0 1 b0d;0.01 13 1823T 3 A Phe608Ile NS 0 0 1 b0d;0.01 13 1927G 3 A Val643Met NS 0 0 1 b0d;0.01 14 1989G 3 T Trp663Stop NS 0 0 1 b0d;0.01 14 2005delAT FS NS 0 0 3 b0d;0.01 14 2041C 3 T Arg681Stop NS 0 0 2 b0d;0.01 14 2147C 3 T Thr716Met NS 0 0 1 b0d;0.01 15 2291G 3 A Cys764Tyr NS 0 0 1 b0d;0.01 15 2294G 3 A Ser765Asn NS 0 0 1 b0d;0.01 15 2300T 3 A Val767Asp NS 0 0 2 b0d;0.01 16 2385del16bp FS NS 0 0 1 b0d;0.01 16 2453G 3 A Gly818Glu NS 0 0 1 b0d;0.01 16 2461T 3 A Trp821Arg NS 0 0 1 b0d;0.01 16 2546T 3 C Val849Ala NS 0 0 4 b0d;0.01 16 2552G 3 A Gly851Asp NS 0 0 1 b0d;0.01 16 2560G 3 A Ala854Thr NS 0 0 1 b0d;0.01 17 2588G 3 C Gly863Ala 0.0006 No 2 2 28 0.02 17 2617T 3 C Phe873Leu NS 0 0 1 b0d;0.01 18 2690C 3 T Thr897Ile NS 0 0 1 b0d;0.01 18 2701A 3 G Thr901Ala NS 0 1 0 b0d;0.01 18 2703A 3 G Thr901Arg NS 0 0 2 b0d;0.01 19 2828G 3 A Arg943Gln NS 20 13 37 0.05 19 2883delC FS NS 0 0 1 b0d;0.01 20 2894A 3 G Asn965Ser NS 0 0 3 b0d;0.01 19 2912C 3 A Thr971Asn NS 0 0 1 b0d;0.01 19 2915C 3 A Thr972Asn NS 0 0 1 b0d;0.01 20 2920T 3 C Ser974Pro NS 0 0 1 b0d;0.01 20 2966T 3 C Val989Ala NS 0 0 2 b0d;0.01 20 2977del8bp FS NS 0 0 1 b0d;0.01 20 3041T 3 G Leu1014Arg NS 0 0 1 b0d;0.01 21 3055A 3 G Thr1019Ala NS 0 0 1 b0d;0.01 21 3064G 3 A Glu1022Lys NS 0 0 1 b0d;0.01 21 3091A 3 G Lys1031Glu NS 0 0 1 b0d;0.01 21 3113G 3 T Ala1038Val 0.001 Yes 1 0 17 0.01 22 3205insAA FS NS 0 0 1 b0d;0.01 22 3261G 3 A Glu1087Lys NS 0 0 2 b0d;0.01 22 3322C 3 T Arg1108Cys 0.04 Yes 0 0 6 b0d;0.01 22 3323G 3 A Arg1108His NS 0 0 1 b0d;0.01 23 3364G 3 A Glu1122Lys NS 0 0 1 b0d;0.01 (continues) Exon Nucleotide Change Effect (A) (B) AMD (n d1d; 182) Control (n d1d; 96) STGD (n d1d; 374) Allele Prevalence 23 3386G 3 T Arg1129Leu NS 0 0 3 b0d;0.01 24 3531C 3 A Cys1158Stop NS 0 0 1 b0d;0.01 25 3749T 3 C Leu1250Pro NS 0 0 1 b0d;0.01 26 3835delGATTCT FS NS 0 0 1 b0d;0.01 27 3940C 3 A Pro1314Thr NS 0 1 0 b0d;0.01 28 4139C 3 T Pro1380Leu 0.001 Yes 0 0 10 0.01 28 4222T 3 C Trp1408Arg NS 0 0 2 b0d;0.01 28 4223G 3 T Trp1408Leu NS 0 0 2 b0d;0.01 28 4234C 3 T Gln1412stop NS 0 0 1 b0d;0.01 29 4297G 3 A Val1433Ile NS 1 0 0 b0d;0.01 29 4319T 3 C Phe1440Ser NS 0 0 1 b0d;0.01 30 4353 afa; 1g 3 t Splice site NS 0 0 1 b0d;0.01 30 4457C 3 T Pro1486Leu NS 0 0 1 b0d;0.01 30 4462T 3 C Cys1488Arg NS 0 0 3 b0d;0.01 30 4463G 3 T Cys1488Phe NS 0 0 2 b0d;0.01 30 4469G 3 A Cys1490Tyr NS 0 0 3 b0d;0.01 30 4531insC FS NS 0 0 2 b0d;0.01 32 4538A 3 G Gln1513Arg NS 0 0 1 b0d;0.01 30 4539 af9; 1g 3 t Splice site NS 0 0 1 b0d;0.01 31 4574T 3 C Leu1525Pro NS 0 0 1 b0d;0.01 33 4733delGTTT FS NS 0 0 1 b0d;0.01 4859delATAACAinsTCC 35 T FS NS 0 0 1 b0d;0.01 36 4909G 3 A Ala1637Thr NS 0 0 1 b0d;0.01 35 4918C 3 T Arg1640Trp NS 0 0 1 b0d;0.01 35 4919G 3 A Arg1640Gln NS 0 0 1 b0d;0.01 35 4954T 3 G Tyr1652Asp NS 0 0 1 b0d;0.01 36 5077G 3 A Val1693Ile NS 0 0 1 b0d;0.01 36 5186T 3 C Leu1729Pro NS 0 0 2 b0d;0.01 36 5206T 3 C Ser1736Pro NS 0 0 1 b0d;0.01 36 5212del11bp FS NS 0 0 1 b0d;0.01 37 5225delTGGTGGTGGGC FS NS 0 0 1 b0d;0.01 del LPA 37 5278del9bp 1760 NS 0 0 1 b0d;0.01 37 5288delG FS NS 0 0 1 b0d;0.01 38 5395A 3 G Asn1799Asp NS 0 0 1 b0d;0.01 38 5451T 3 G Asp1817Glu NS 1 0 4 b0d;0.01 39 5584 af9; 5g 3 a Splice site 0.02 Yes 0 0 6 b0d;0.01 40 5603A 3 T Asn1868Ile 0.0006 No 20 7 79 0.08 40 5651T 3 A Val1884GLu NS 0 0 1 b0d;0.01 40 5657G 3 A Gly1886Glu NS 0 0 1 b0d;0.01 40 5687T 3 A Val1896Asp NS 0 0 1 b0d;0.01 40 5693G 3 A Arg1898His NS 0 0 1 b0d;0.01 40 5714 af9; 5g 3 a Splice site NS 0 0 1 b0d;0.01 42 5843CA 3 TG Pro1948Leu NS 11 7 28 0.04 42 5882G 3 A Gly1961Glu b0d;0.0001 Yes 1 0 43 0.03 43 5908C 3 T Leu1970Phe NS 1 0 1 b0d;0.01 43 5917delG FS NS 0 0 1 b0d;0.01 44 6079C 3 T Leu2027Phe 0.01 Yes 0 0 9 0.01 44 6088C 3 T Arg2030Stop NS 0 0 2 b0d;0.01 44 6089G 3 A Arg2030Gln NS 0 0 1 b0d;0.01 44 6112A 3 T Arg2038Trp NS 0 0 1 b0d;0.01 45 6148A 3 C Val2050Leu NS 1 0 0 b0d;0.01 46 6212A 3 T Tyr2071Phe NS 0 0 1 b0d;0.01 45 6229C 3 T Arg2077Trp NS 0 0 2 b0d;0.01 46 6320G 3 A Arg2107His 0.01 Yes 0 0 10 0.01 46 6383A 3 G His2128Arg NS 0 0 1 b0d;0.01 47 6446G 3 T Arg2149Leu NS 0 0 1 b0d;0.01 47 6449G 3 A Cys2150Tyr NS 0 0 5 b0d;0.01 48 6529G 3 A Asp2177Asn NS 2 0 0 b0d;0.01 48 6686T 3 C Leu2229Pro NS 0 0 1 b0d;0.01 48 6707delTCACACAG FS NS 0 0 1 b0d;0.01 48 6729 af9; 1g 3 a Splice site NS 0 0 1 b0d;0.01 49 6764G 3 T Ser2255Ile 0.009 No 16 4 54 0.06 49 6788G 3 T Arg2263Leu NS 0 0 1 b0d;0.01 (A) The probability under the null hypothesis of similar prevalence of each variant in Stargardt (STGD) compared with non-STGD alleles (two-tailed Fisher`s exact test); (B) compatability of the variant existing in a ratio of 100:1 in STGD to control alleles, calculated using the binomial distribution. 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[hide] Late-onset Stargardt disease is associated with mi... Hum Genet. 2001 Apr;108(4):346-55. Yatsenko AN, Shroyer NF, Lewis RA, Lupski JR
Late-onset Stargardt disease is associated with missense mutations that map outside known functional regions of ABCR (ABCA4).
Hum Genet. 2001 Apr;108(4):346-55., [PMID:11379881]

Abstract [show]
Based on recent studies of the photoreceptor-specific ABC transporter gene ABCR (ABCA4) in Stargardt disease (STGD1) and other retinal dystrophies, we and others have developed a model in which the severity of retinal disease correlates inversely with residual ABCR activity. This model predicts that patients with late-onset STGDI may retain partial ABCR activity attributable to mild missense alleles. To test this hypothesis, we used late-onset STGDI patients (onset: > or =35 years) to provide an in vivo functional analysis of various combinations of mutant alleles. We sequenced directly the entire coding region of ABCR and detected mutations in 33/50 (66%) disease chromosomes, but surprisingly, 11/33 (33%) were truncating alleles. Importantly, all 22 missense mutations were located outside the known functional domains of ABCR (ATP-binding or transmembrane), whereas in our general cohort of STGDI subjects, alterations occurred with equal frequency across the entire protein. We suggest that these missense mutations in regions of unknown function are milder alleles and more susceptible to modifier effects. Thus, we have corroborated a prediction from the model of ABCR pathogenicity that (1) one mutant ABCR allele is always missense in late-onset STGD1 patients, and (2) the age-of-onset is correlated with the amount of ABCR activity of this allele. In addition, we report three new pseudodominant families that now comprise eight of 178 outbred STGD1 families and suggest a carrier frequency of STGD1-associated ABCR mutations of about 4.5% (approximately 1/22).

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111 To compare this observation directly with our previous report (Lewis et al. 1999), we replaced five mutations (A1038V, L2027F, R2030Q, R2038W, V2050L) to linker regions. Login to comment

[hide] Molecular genetic analysis of ABCR gene in Japanes... Jpn J Ophthalmol. 2000 May-Jun;44(3):245-9. Fuse N, Suzuki T, Wada Y, Yoshida M, Shimura M, Abe T, Nakazawa M, Tamai M
Molecular genetic analysis of ABCR gene in Japanese dry form age-related macular degeneration.
Jpn J Ophthalmol. 2000 May-Jun;44(3):245-9., [PMID:10913642]

Abstract [show]
PURPOSE: To explore whether the mutation in the retina-specific ATP-binding cassette transporter (ABCR) gene, the Stargardt's disease gene, contributes to the prevalence of the dry form of age-related macular degeneration (dry AMD) in Japanese unrelated patients. METHODS: Twenty-five Japanese unrelated patients with dry AMD who were diagnosed by fluorescein angiography and indocyanine green angiography were chosen as the dry AMD group. None of these cases had apparent choroidal neovascularization. To detect the mutations in the ABCR gene, genomic DNA was extracted from leukocytes of peripheral blood, and 26 exons of the ABCR gene were amplified by polymerase chain reaction (PCR). All the PCR products were then directly sequenced. When a mutation was detected, the occurrence of a mutation was compared between these AMD patients and the control group. RESULTS: After direct sequencing, a point mutation in exon 29 was found in one of the 25 dry AMD patients. In addition, a polymorphism in exon 45 was found in two other patients, and three sequence variations in exon 23 were detected in all patients. The incidence in AMD patients in whom a mutation in exon 29 (4%) was detected was less than that in controls (5%). Screening of the intron-exon boundaries also led to the identification of intronic mutation in intron 33. CONCLUSION: In this study we found no relationship between allelic variation in the ABCR gene and the prevalence of dry AMD in Japanese unrelated patients.

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31 Mutations Found in ABCR* Gene in 26 Exons Examined in This Study Exon AMD† Stargardt`s Disease Exon AMD Stargardt`s Disease 11 E471K 29 T1428M 15 31 R1517S 16 G818E, G863A (D847H) 33 I1562T G1578R 17 34 N1614FS 18 35 19 V931M, 2884delC N965M, (R943Q) 36 5196ϩ1G→A 5041deL15 5196ϩ2T→C 20 40 R1898H R1898H 21 A1028V 42 G1961E G1961E 22 3211insGT, V1072A E1087K 43 L1970F 6006ϩ1G→T 23 R1129L 44 L2027F, R2038W (I2023I) 24 45 V2050L, R2077W (I2083I) 25 46 R2106C (V2094V) 27 48 6519⌬11bp D2177N 6568⌬C 6519⌬11bp 6709insG *ABCR: ATP-binding cassette transporter. Login to comment

[hide] Genotype/Phenotype analysis of a photoreceptor-spe... Am J Hum Genet. 1999 Feb;64(2):422-34. Lewis RA, Shroyer NF, Singh N, Allikmets R, Hutchinson A, Li Y, Lupski JR, Leppert M, Dean M
Genotype/Phenotype analysis of a photoreceptor-specific ATP-binding cassette transporter gene, ABCR, in Stargardt disease.
Am J Hum Genet. 1999 Feb;64(2):422-34., [PMID:9973280]

Abstract [show]
Mutation scanning and direct DNA sequencing of all 50 exons of ABCR were completed for 150 families segregating recessive Stargardt disease (STGD1). ABCR variations were identified in 173 (57%) disease chromosomes, the majority of which represent missense amino acid substitutions. These ABCR variants were not found in 220 unaffected control individuals (440 chromosomes) but do cosegregate with the disease in these families with STGD1, and many occur in conserved functional domains. Missense amino acid substitutions located in the amino terminal one-third of the protein appear to be associated with earlier onset of the disease and may represent misfolding alleles. The two most common mutant alleles, G1961E and A1038V, each identified in 16 of 173 disease chromosomes, composed 18.5% of mutations identified. G1961E has been associated previously, at a statistically significant level in the heterozygous state, with age-related macular degeneration (AMD). Clinical evaluation of these 150 families with STGD1 revealed a high frequency of AMD in first- and second-degree relatives. These findings support the hypothesis that compound heterozygous ABCR mutations are responsible for STGD1 and that some heterozygous ABCR mutations may enhance susceptibility to AMD.

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76 2 0071GrA R24H 1 19 2894ArG N965S 3 36 5196ϩ1GrA Splice 2 3 0161GrA C54Y 1 21 3113CrT A1038V 16 5196ϩ2TrC Splice 1 0179CrT A60V 1 22 3211insGT FS 1 37 5281del9 PAL1761del 1 0203CrG P68R 1 3212CrT S1071L 1 38 5459GrC R1820P 1 0223TrG C75G 1 3215TrC V1072A 1 39 5512CrT H1838Y 1 6 0634CrT R212C 1 3259GrA E1087K 1 5527CrT R1843W 1 0664del13 FS 1 3322CrT R1108C 6 40 5585-1GrA Splice 1 0746ArG D249G 1 23 3364GrA E1122K 1 5657GrA G1886E 1 8 1007CrG S336C 1 3385GrT R1129C 1 5693GrA R1898H 4 1018TrG Y340D 1 3386GrT R1129L 2 5714ϩ5GrA Splice 8 11 1411GrA E471K 1 24 3602TrG L1201R 1 42 5882GrA G1961E 16 12 1569TrG D523E 1 25 3610GrA D1204N 1 5898ϩ1GrT Splice 3 1622TrC L541P 1 28 4139CrT P1380L 4 43 5908CrT L1970F 1 1715GrA R572Q 2 4216CrT H1406Y 1 5929GrA G1977S 1 1715GrC R572P 1 4222TrC W1408R 4 6005ϩ1GrT Splice 1 13 1804CrT R602W 1 4232insTATG FS 1 44 6079CrT L2027F 11 1822TrA F608I 2 4253ϩ5GrT Splice 1 6088CrT R2030X 1 1917CrA Y639X 1 29 4297GrA V1433I 1 6089GrA R2030Q 1 1933GrA D645N 1 4316GrA G1439D 2 6112CrT R2038W 1 14 2005delAT FS 1 4319TrC F1440S 1 45 6148GrC V2050L 2 2090GrA W697X 1 4346GrA W1449X 1 6166ArT K2056X 1 2160ϩ1GrC Splice 1 30a 4462TrC C1488R 2 6229CrT R2077W 1 16 2453GrA G818E 1 4457CrT P1486L 1 46 6286GrA E2096K 1 2461TrA W821R 1 30b 4469GrA C1490Y 3 6316CrT R2106C 1 2536GrC D846H 1 4539ϩ1GrT Splice 1 47 6391GrA E2131K 1 2552GrC G851D 1 31 4577CrT T1526M 7 6415CrT R2139W 1 17 2588GrC G863A 11 4594GrA D1532N 3 6445CrT R2149X 1 19 2791GrA V931M 2 35 4947delC FS 1 48 6543del36 1181del12 1 2827CrT R943W 1 36 5041del15 VVAIC1681del 2 6709insG FS 1 2884delC FS 1 5087GrA S1696N 1 NOTE.-FS ϭ frameshift. Login to comment
101 For the double-mutant chromosomes in the compound heterozygous families (AR31: Y340D and R572Q; AR106: E471K and E2131K; AR128: R572Q and G863A; and AR189: L541P and A1038V) and in those families in which the second disease chromosome was not identified (AR215: H1406Y and V2050L; AR264: D1204N and L2027F; AR254: D249G and R1898H; AR265: G863A and R1898H; AR285: 2714ϩ5GrA and 2884delC; and AR305: G863A and R1898H), in three cases (AR128, AR265, and AR305) each mutation on the double-mutant chromosome had been identified independently as disease causing in other, unrelated families with STGD1 (table 1). Login to comment
77 2 0071GrA R24H 1 19 2894ArG N965S 3 36 5196af9;1GrA Splice 2 3 0161GrA C54Y 1 21 3113CrT A1038V 16 5196af9;2TrC Splice 1 0179CrT A60V 1 22 3211insGT FS 1 37 5281del9 PAL1761del 1 0203CrG P68R 1 3212CrT S1071L 1 38 5459GrC R1820P 1 0223TrG C75G 1 3215TrC V1072A 1 39 5512CrT H1838Y 1 6 0634CrT R212C 1 3259GrA E1087K 1 5527CrT R1843W 1 0664del13 FS 1 3322CrT R1108C 6 40 5585afa;1GrA Splice 1 0746ArG D249G 1 23 3364GrA E1122K 1 5657GrA G1886E 1 8 1007CrG S336C 1 3385GrT R1129C 1 5693GrA R1898H 4 1018TrG Y340D 1 3386GrT R1129L 2 5714af9;5GrA Splice 8 11 1411GrA E471K 1 24 3602TrG L1201R 1 42 5882GrA G1961E 16 12 1569TrG D523E 1 25 3610GrA D1204N 1 5898af9;1GrT Splice 3 1622TrC L541P 1 28 4139CrT P1380L 4 43 5908CrT L1970F 1 1715GrA R572Q 2 4216CrT H1406Y 1 5929GrA G1977S 1 1715GrC R572P 1 4222TrC W1408R 4 6005af9;1GrT Splice 1 13 1804CrT R602W 1 4232insTATG FS 1 44 6079CrT L2027F 11 1822TrA F608I 2 4253af9;5GrT Splice 1 6088CrT R2030X 1 1917CrA Y639X 1 29 4297GrA V1433I 1 6089GrA R2030Q 1 1933GrA D645N 1 4316GrA G1439D 2 6112CrT R2038W 1 14 2005delAT FS 1 4319TrC F1440S 1 45 6148GrC V2050L 2 2090GrA W697X 1 4346GrA W1449X 1 6166ArT K2056X 1 2160af9;1GrC Splice 1 30a 4462TrC C1488R 2 6229CrT R2077W 1 16 2453GrA G818E 1 4457CrT P1486L 1 46 6286GrA E2096K 1 2461TrA W821R 1 30b 4469GrA C1490Y 3 6316CrT R2106C 1 2536GrC D846H 1 4539af9;1GrT Splice 1 47 6391GrA E2131K 1 2552GrC G851D 1 31 4577CrT T1526M 7 6415CrT R2139W 1 17 2588GrC G863A 11 4594GrA D1532N 3 6445CrT R2149X 1 19 2791GrA V931M 2 35 4947delC FS 1 48 6543del36 1181del12 1 2827CrT R943W 1 36 5041del15 VVAIC1681del 2 6709insG FS 1 2884delC FS 1 5087GrA S1696N 1 NOTE.-FS afd; frameshift. Login to comment
102 For the double-mutant chromosomes in the compound heterozygous families (AR31: Y340D and R572Q; AR106: E471K and E2131K; AR128: R572Q and G863A; and AR189: L541P and A1038V) and in those families in which the second disease chromosome was not identified (AR215: H1406Y and V2050L; AR264: D1204N and L2027F; AR254: D249G and R1898H; AR265: G863A and R1898H; AR285: 2714af9;5GrA and 2884delC; and AR305: G863A and R1898H), in three cases (AR128, AR265, and AR305) each mutation on the double-mutant chromosome had been identified independently as disease causing in other, unrelated families with STGD1 (table 1). Login to comment

[hide] Exome sequencing of index patients with retinal dy... PLoS One. 2013 Jun 14;8(6):e65574. doi: 10.1371/journal.pone.0065574. Print 2013. Corton M, Nishiguchi KM, Avila-Fernandez A, Nikopoulos K, Riveiro-Alvarez R, Tatu SD, Ayuso C, Rivolta C
Exome sequencing of index patients with retinal dystrophies as a tool for molecular diagnosis.
PLoS One. 2013 Jun 14;8(6):e65574. doi: 10.1371/journal.pone.0065574. Print 2013., [PMID:23940504]

Abstract [show]
BACKGROUND: Retinal dystrophies (RD) are a group of hereditary diseases that lead to debilitating visual impairment and are usually transmitted as a Mendelian trait. Pathogenic mutations can occur in any of the 100 or more disease genes identified so far, making molecular diagnosis a rather laborious process. In this work we explored the use of whole exome sequencing (WES) as a tool for identification of RD mutations, with the aim of assessing its applicability in a diagnostic context. METHODOLOGY/PRINCIPAL FINDINGS: We ascertained 12 Spanish families with seemingly recessive RD. All of the index patients underwent mutational pre-screening by chip-based sequence hybridization and resulted to be negative for known RD mutations. With the exception of one pedigree, to simulate a standard diagnostic scenario we processed by WES only the DNA from the index patient of each family, followed by in silico data analysis. We successfully identified causative mutations in patients from 10 different families, which were later verified by Sanger sequencing and co-segregation analyses. Specifically, we detected pathogenic DNA variants ( approximately 50% novel mutations) in the genes RP1, USH2A, CNGB3, NMNAT1, CHM, and ABCA4, responsible for retinitis pigmentosa, Usher syndrome, achromatopsia, Leber congenital amaurosis, choroideremia, or recessive Stargardt/cone-rod dystrophy cases. CONCLUSIONS/SIGNIFICANCE: Despite the absence of genetic information from other family members that could help excluding nonpathogenic DNA variants, we could detect causative mutations in a variety of genes known to represent a wide spectrum of clinical phenotypes in 83% of the patients analyzed. Considering the constant drop in costs for human exome sequencing and the relative simplicity of the analyses made, this technique could represent a valuable tool for molecular diagnostics or genetic research, even in cases for which no genotypes from family members are available.

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105 FAMILY ID INDEX PATIENT ID GENE (OMIM entry) NUCLEOTIDE CHANGE PROTEIN CHANGE NOVEL/KNOWN REFERENCE RP-0674 01-0570 ABCA4 c.287delA p.N96Tfs*19 novel (601691) c.6148G.C p.V2050L known [43] RP-0298 95-0103 ABCA4 c.4720G.T p.E1574* known [44] c.950delG p.G317Afs*57 novel RP-1102 07-0366 ABCA4 c.2285C.A (homoz) p.A762E known [45] RP-1164 07-0360 CHM (300390) c.863dupA p.M289Y*18 novel RP-1263 08-0177 USH2A c.920_923dupGCCA p.H308Qfs*16 known [46] (608400) c.12574C.T p.R4192C novel RP-1659 10-1367 CNGB3 c.1148delC p.T383Ifs*13 known [31] (605080) c.1666G.T p.E556* novel RP-1174 04-0834 CNGB3 c.1148delC (homoz) p.T383Ifs*13 known [31] RP-0137 1601 RP1 c.1625C.G p.S542* novel (603937) c.4804C.T p.Q1602* novel RP-0235 2343 RP1 c.5173C.T (homoz) p.Q1725* novel RP-1116 06-1075 NMNAT1 c.507G.A p.W169* known [47] (608700) c.769G.A p.E257K known [47] doi:10.1371/journal.pone.0065574.t001 clinical phenotype of the patients, and/or the sequencing/ mapping methods of NGS itself. Login to comment

[hide] Clinical and molecular analysis of Stargardt disea... Am J Ophthalmol. 2013 Sep;156(3):487-501.e1. doi: 10.1016/j.ajo.2013.05.003. Fujinami K, Sergouniotis PI, Davidson AE, Wright G, Chana RK, Tsunoda K, Tsubota K, Egan CA, Robson AG, Moore AT, Holder GE, Michaelides M, Webster AR
Clinical and molecular analysis of Stargardt disease with preserved foveal structure and function.
Am J Ophthalmol. 2013 Sep;156(3):487-501.e1. doi: 10.1016/j.ajo.2013.05.003., [PMID:23953153]

Abstract [show]
PURPOSE: To describe a cohort of patients with Stargardt disease who show a foveal-sparing phenotype. DESIGN: Retrospective case series. METHODS: The foveal-sparing phenotype was defined as foveal preservation on autofluorescence imaging, despite a retinopathy otherwise consistent with Stargardt disease. Forty such individuals were ascertained and a full ophthalmic examination was undertaken. Following mutation screening of ABCA4, the molecular findings were compared with those of patients with Stargardt disease but no foveal sparing. RESULTS: The median age of onset and age at examination of 40 patients with the foveal-sparing phenotype were 43.5 and 46.5 years. The median logMAR visual acuity was 0.18. Twenty-two patients (22/40, 55%) had patchy parafoveal atrophy and flecks; 8 (20%) had numerous flecks at the posterior pole without atrophy; 7 (17.5%) had mottled retinal pigment epithelial changes; 2 (5%) had multiple atrophic lesions, extending beyond the arcades; and 1 (2.5%) had a bull's-eye appearance. The median central foveal thickness assessed with spectral-domain optical coherence tomographic images was 183.0 mum (n = 33), with outer retinal tubulation observed in 15 (45%). Twenty-two of 33 subjects (67%) had electrophysiological evidence of macular dysfunction without generalized retinal dysfunction. Disease-causing variants were found in 31 patients (31/40, 78%). There was a higher prevalence of the variant p.Arg2030Gln in the cohort with foveal sparing compared to the group with foveal atrophy (6.45% vs 1.07%). CONCLUSIONS: The distinct clinical and molecular characteristics of patients with the foveal-sparing phenotype are described. The presence of 2 distinct phenotypes of Stargardt disease (foveal sparing and foveal atrophy) suggests that there may be more than 1 disease mechanism in ABCA4 retinopathy.

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142 Allele Frequencies of 72 ABCA4 Variants Identified in a Comparison Groupa With the Typical Stargardt Disease (140 Patients Without Evidence of Foveal Sparing on Autofluorescence Imaging) (Continued) Exon Nucleotide Substitution and Amino Acid Change Number of Alleles Allele Frequency Int 33 c.4773&#fe;48C>T 1 0.36% 34 c.4793C>A, p.Ala1598Asp 1 0.36% 35 c.c.4918C>T, p.Arg1640Trp 1 0.36% Int 35 c.5018&#fe;2T>C, Splice site 2 0.71% 36 c.5114G>A, p.Arg1705Gln 2 0.71% 37 c.5222_5233delTGGTGGTGGGC, p.Lys1741Hisfs 1 0.36% 37 c.5281_5289delCTT CCT GCC, p.Pro1761_Leu1763del 2 0.71% Int 38 c.5461-10T>C 23 8.21% Int 39 c.5585-1G>A, Splice site 1 0.36% Int 40 c.5714&#fe;5G>A, Splice site 5 1.79% 42 c.5882G>A, p.Gly1961Glu 17 6.07% 43 c.5908C>T, p.Leu1970Phe 2 0.71% 43 c.5917delG, p.Val1973* 1 0.36% 44 c.6079C>T, p.Leu2027Phe 10 3.57% 44 c.6089G>A, p.Arg2030Gln 3 1.07% 44 c.6118C>T, p.Arg2040* 1 0.36% 45 c.6148G>C, p.Val2050Leu 3 1.43% 46 c.6286G>A, p.Glu2096Lys 1 0.36% 46 c.6320G>A, p.Arg2107His 4 1.43% 47 c.6445C>T, p.Arg2149* 1 0.36% 47 c.6449G>A, p.Cys2150Tyr 3 1.07% 48 c.6658C>T, p.Gln2220* 3 1.07% 48 c.6709_6710insG, p.Thr2237Serfs 1 0.36% Int &#bc; Intron. Login to comment

[hide] Targeted Next-Generation Sequencing Improves the D... Invest Ophthalmol Vis Sci. 2015 Apr;56(4):2173-82. doi: 10.1167/iovs.14-16178. Fernandez-San Jose P, Corton M, Blanco-Kelly F, Avila-Fernandez A, Lopez-Martinez MA, Sanchez-Navarro I, Sanchez-Alcudia R, Perez-Carro R, Zurita O, Sanchez-Bolivar N, Lopez-Molina MI, Garcia-Sandoval B, Riveiro-Alvarez R, Ayuso C
Targeted Next-Generation Sequencing Improves the Diagnosis of Autosomal Dominant Retinitis Pigmentosa in Spanish Patients.
Invest Ophthalmol Vis Sci. 2015 Apr;56(4):2173-82. doi: 10.1167/iovs.14-16178., [PMID:25698705]

Abstract [show]
PURPOSE: Next-generation sequencing (NGS) has been demonstrated to be an effective strategy for the detection of mutations in retinal dystrophies, a group of inherited diseases that are highly heterogeneous. Therefore, the aim of this study is the application of an NGS-based approach in a Spanish cohort of autosomal dominant retinitis pigmentosa (RP) patients to find out causative mutations. METHODS: Index cases of 59 Spanish families with initial diagnosis of autosomal dominant RP and unsuccessfully studied for mutations in the most common RP causal genes, were selected for application of a NGS-based approach with a custom panel for 73 genes related to retinal dystrophies. Candidate variants were select based on frequency, pathogenicity, inherited model, and phenotype. Subsequently, confirmation by Sanger sequencing, cosegregation analysis, and population studies, was applied for determining the implication of those variants in the pathology. RESULTS: Overall 31 candidate variants were selected. From them, 17 variants were considered as mutations causative of the disease, 64% (11/17) of them were novel and 36% (6/17) were known RP-related mutations. Therefore, applying this technology16 families were characterized rendering a mutation detection rate of 27% (16/59). Of them, 5% (3/59) of cases displayed mutations in recessive or X-linked genes (ABCA4, RPGR, and RP2) allowing a genetic and clinical reclassification of those families. Furthermore, seven novel variants with uncertain significance and seven novel variants probably not causative of disease were also found. CONCLUSIONS: This NGS strategy is a fast, effective, and reliable tool to detect known and novel mutations in autosomal dominant RP patients allowing genetic reclassification in some cases and increasing the knowledge of pathogenesis in retinal dystrophies.

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79 Spectrum of Variants Causative of the Disease Identified With the RD_NGS_Panel in Autosomal Dominant Retinitis Pigmentosa Families Family Gene NM HGVS-cdna HGVS-prot Effect Zyg dbSNP (MAF) SIFT Polyphen-2 Mutation Taster Human Splicing Finder Cosegregation (Affected/ Unaffected/ Asymptomatic) Frequency in Spanish Control Alleles Reference Known mutations RP-1875 ABCA4* NM_000350.2 c.3386G>T p.Arg1129Leu Missense Het rs1801269 (<0.01) D (0) Pr-D (0.992) DC (1.000) - Yes (2/11 ) 0/150 Allikmets et al., 28 1997 c.6148G>C p.Val2050Leu Missense Het rs41292677 (0.04) D (0.01) Pr-D (0.950) DC (0.999) - 0/150 Allikmets et al., 29 1997 RP-1688 CRX NM_000554.4 c.586_587insC p.Ala198Glyfs*38 Frameshift Het - - - DC (1.000) - NA 0/150 Sohocki et al., 30 1998 RP-1970 PRPF31 NM_015629.3 c.1146&#fe;2T>C - Splicing Het - - - DC (1.000) Decrease 5 0 donor site of exon 11 (90.88->72.59) Yes (2) 0/150 Waseem et al., 31 2007 RP-0642 RHO NM_000539.3 c.44A>G p.Asn15Ser Missense Het rs104893786 (nfd) D (0) Pr-D (0.998) DC (1.000) - Yes (1/2) 0/150 Kranich et al., 32 1993 RP-1480 SNRNP200 NM_014014.4 c.3260C>T p.Ser1087Leu Missense Het - D (0) Pr-D (0.995) DC (1.000) - Yes (4/4/4) 0/150 Zhao et al., 33 2009 Novel LOF protein mutations RP-1541 PRPF31 NM_015629.3 c.937_938insA p.Gly314Argfs*10 Frameshift Het - - - DC (1.000) - Yes (2/2) 0/150 This study RP-1176 PRPH2 NM_000322.4 c.582-1G>A - Splicing Het - - - - Decrease 3 0 acceptor site of exon 2 (82.97->54.03) Yes (2) 0/150 This study RP-2072 RP1 NM_006269.1 c.1981G>T p.Glu661* Nonsense Het - - - DC (1.000) - NA 0/150 This study RP-1890 RP1 NM_006269.1 c.2286delA p.Asn763Ilefs*12 Frameshift Het - - - DC (1.000) - Yes (2) 0/150 This study RP-1387 RP1 NM_006269.1 c.2745_2749del p.Tyr915* Nonsense Het - - - DC (1.000) - Yes (4/2) 0/150 This study RP-0631 RPGR* NM_000328.2 c.1234C>T p.Arg412* Nonsense Het - - - DC (1.000) - Yes (2) 0/150 This study Novel nonsynonymous/in-frame mutations RP-1728 GUCA1B NM_002098.5 c.131G>A p.Arg44His Missense Het - D (0.004) B (0.065) DC (0.997) - Yes (2/1) 0/300 This study RP-0422 IMPDH1 NM_000883.3 c.962C>T p.Ala321Val Missense Het - D (0) Pr-D (0.926) DC (1.000) - Yes (3/11) 0/300 This study RP-0652 PRPH2 NM_000322.4 c.536G>T p.Trp179Leu Missense Het - D (0.010) Pr-D (1.000) DC (1.000) - Yes (2) 0/300 This study RP-0948 RP1 NM_006269.1 c.4328G>A p.Arg1443Gln Missense Het - D (0) Pr-D (0.974) P (0.993) - Yes (2/1) 0/300 This study RP-1682 RP2* NM_006915.2 c.9_11del p.Phe4del In-frame Het - - - DC (0.986) - Yes (1/3) 0/300 This study LOF, loss of function; Zyg, zygosity; Het, heterozygosis; nfd, no frequency data; SIFT, deleterious (D); Polyphen2: probably damaging (Pr-D) and benign (B); Mutation Taster: disease causing (DC) and polymorphism (P); NA, not available. Login to comment
84 Two known compound heterozygous mutations (p.Arg1129Leu) and (p.Val2050Leu) in the ABCA4 gene were detected in one family, and two novel mutations in the chromosome X genes, RPGR (p.Arg412*) and RP2 (p.Phe4del). Login to comment

[hide] Common synonymous variants in ABCA4 are protective... BMC Ophthalmol. 2015 Mar 6;15:18. doi: 10.1186/s12886-015-0008-0. Grassmann F, Bergholz R, Mandl J, Jagle H, Ruether K, Weber BH
Common synonymous variants in ABCA4 are protective for chloroquine induced maculopathy (toxic maculopathy).
BMC Ophthalmol. 2015 Mar 6;15:18. doi: 10.1186/s12886-015-0008-0., [PMID:25884411]

Abstract [show]
BACKGROUND: Chloroquine (CQ) and hydroxychloroquine (HCQ) are used to treat auto-immune related diseases such as rheumatoid arthritis (RA) or systemic lupus erythematosus. Both drugs however can cause retinal toxicity eventually leading to irreversible maculopathy and retinopathy. Established risk factors are duration and dosage of treatment while the involvement of genetic factors contributing to toxic maculopathy is largely unclear. To address the latter issue, this study aimed to expand on earlier efforts by (1) evaluating risk-altering variants known to be associated with age-related macular degeneration (AMD), a frequent maculopathy in individuals over 55 years of age, and (2) determining the contribution of genetic variants in the coding sequence of the ABCA4 gene. METHODS: The ABCA4 gene was analyzed by deep sequencing technology using a personal genome machine (Ion Torrent) with 200 bp read length. Assessment of AMD variants was done by restriction enzyme digestion of PCR products and TaqMan SNP genotyping. Effect sizes, p-values and confidence intervals of common variants were evaluated by logistic regression (Firth's bias corrected). To account for multiple testing, p-values were adjusted according to the false discovery rate. RESULTS: We found no effects of known AMD-associated variants on the risk of toxic maculopathy. In contrast, we report a statistically significant association of common variants in the ABCA4 gene with retinal disease, assessed by a score-based variance-component test (PSKAT = 0.0055). This association remained significant after adjustment for environmental factors like age and duration of medication and was driven by three common variants in ABCA4 (c.5682G > C, c.5814A > G, c.5844A > G), all conferring a reduced risk for toxic maculopathy. CONCLUSIONS: Our findings demonstrate that minor alleles of common genetic variants in ABCA4 significantly reduce susceptibility to develop toxic maculopathy under CQ treatment. A refined risk profile based on genetic and environmental factors may have implications for revised recommendations in CQ as well as HCQ treatment.

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95 Table 2 Genetic variants identified in ABCA4 sequence analysis in CQ-treated patients with (cases) and without (controls) toxic maculopathy Frequency in Variant (NM_000350.2) Amino acid exchange (NP_000341.2) Cases Controls EURߤ Raw p-value FDR# c.324G > A M114I 0.00 0.04 - - - c.635G > A R212H 0.06 0.08 0.06 - - c.1268A > G* H423R 0.29 0.23 0.30 0.58783 0.58783 c.1269C > T H423H 0.13 0.04 0.07 - - c.1622T > C L541P 0.02 0.00 - - - c.2588G > C G863A 0.00 0.04 0.00 - - c.2828G > A R943Q 0.04 0.12 0.04 - - c.3113C > T A1038V 0.02 0.00 0.00 - - c.4203C > A P1401P 0.00 0.04 - - - c.4297G > A V1433I 0.00 0.04 0.00 - - c.5603A > T N1868I 0.06 0.08 0.07 - - c.5682G > C* L1894L 0.13 0.38 0.26 0.02292 0.030 c.5814A > G* L1938L 0.06 0.31 0.18 0.00722 0.014 c.5843C > T P1948L 0.04 0.08 0.04 - - c.5844A > G* P1948P 0.06 0.31 0.19 0.00722 0.014 c.6069T > C I2023I 0.04 0.08 0.06 - c.6148G > C V2050L 0.02 0.00 0.00 - - c.6249C > T I2083I 0.04 0.08 0.05 - - c.6282 + 7G > A - 0.04 0.08 0.05 - - c.6285T > C D2095D 0.08 0.15 0.10 - - c.6357A > G E2119E 0.02 0.00 - - - c.6730-3T > C - 0.02 0.12 0.02 - - c.6764G > T S2255I 0.02 0.12 0.02 - - *Common variants (combined frequency in cases and controls > 11.6%). Login to comment

[hide] Quantitative Fundus Autofluorescence and Optical C... Invest Ophthalmol Vis Sci. 2015 Nov 1;56(12):7274-85. doi: 10.1167/iovs.15-17371. Duncker T, Stein GE, Lee W, Tsang SH, Zernant J, Bearelly S, Hood DC, Greenstein VC, Delori FC, Allikmets R, Sparrow JR
Quantitative Fundus Autofluorescence and Optical Coherence Tomography in ABCA4 Carriers.
Invest Ophthalmol Vis Sci. 2015 Nov 1;56(12):7274-85. doi: 10.1167/iovs.15-17371., [PMID:26551331]

Abstract [show]
PURPOSE: To assess whether carriers of ABCA4 mutations have increased RPE lipofuscin levels based on quantitative fundus autofluorescence (qAF) and whether spectral-domain optical coherence tomography (SD-OCT) reveals structural abnormalities in this cohort. METHODS: Seventy-five individuals who are heterozygous for ABCA4 mutations (mean age, 47.3 years; range, 9-82 years) were recruited as family members of affected patients from 46 unrelated families. For comparison, 57 affected family members with biallelic ABCA4 mutations (mean age, 23.4 years; range, 6-67 years) and two noncarrier siblings were also enrolled. Autofluorescence images (30 degrees , 488-nm excitation) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference. The gray levels (GLs) of each image were calibrated to the reference, zero GL, magnification, and normative optical media density to yield qAF. Horizontal SD-OCT scans through the fovea were obtained and the thicknesses of the outer retinal layers were measured. RESULTS: In 60 of 65 carriers of ABCA4 mutations (age range, 9-60), qAF levels were within normal limits (95% confidence level) observed for healthy noncarrier subjects, while qAF levels of affected family members were significantly increased. Perifoveal fleck-like abnormalities were observed in fundus AF images in four carriers, and corresponding changes were detected in the outer retinal layers in SD-OCT scans. Thicknesses of the outer retinal layers were within the normal range. CONCLUSIONS: With few exceptions, individuals heterozygous for ABCA4 mutations and between the ages of 9 and 60 years do not present with elevated qAF. In a small number of carriers, perifoveal fleck-like changes were visible.

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205 Heterozygous mutations in ABCA4 (p.V2050L) have also been reported to contribute to an exacerbation of the phenotype conferred by a monoallelic mutation in PRPH2 (p.R172W).41 In another study, 12 nonsymptomatic mutation-carrying relatives of STGD1 patients were found to have normal visual acuity but impaired contrast sensitivity and reduced multifocal ERG amplitudes.21 More recently, a subset of ABCA4 carriers were reported to have reduced visual acuity, fundus abnormalities that included pigmentary changes (8/18) and flecks, and multifocal ERGs of reduced amplitude and delayed implicit times.22 Some missense mutations, including the complex allele p. Login to comment

[hide] Next-generation sequencing of ABCA4: High frequenc... Exp Eye Res. 2015 Nov 22;145:93-99. doi: 10.1016/j.exer.2015.11.011. Sciezynska A, Ozieblo D, Ambroziak AM, Korwin M, Szulborski K, Krawczynski M, Stawinski P, Szaflik J, Szaflik JP, Ploski R, Oldak M
Next-generation sequencing of ABCA4: High frequency of complex alleles and novel mutations in patients with retinal dystrophies from Central Europe.
Exp Eye Res. 2015 Nov 22;145:93-99. doi: 10.1016/j.exer.2015.11.011., [PMID:26593885]

Abstract [show]
Variation in the ABCA4 locus has emerged as the most prevalent cause of monogenic retinal diseases. The study aimed to discover causative ABCA4 mutations in a large but not previously investigated cohort with ABCA4-related diseases originating from Central Europe and to refine the genetic relevance of all identified variants based on population evidence. Comprehensive clinical studies were performed to identify patients with Stargardt disease (STGD, n = 76) and cone-rod dystrophy (CRD, n = 16). Next-generation sequencing targeting ABCA4 was applied for a widespread screening of the gene. The results were analyzed in the context of exome data from a corresponding population (n = 594) and other large genomic databases. Our data disprove the pathogenic status of p.V552I and provide more evidence against a causal role of four further ABCA4 variants as drivers of the phenotype under a recessive paradigm. The study identifies 12 novel potentially pathogenic mutations (four of them recurrent) and a novel complex allele p.[(R152*; V2050L)]. In one third (31/92) of our cohort we detected the p.[(L541P; A1038V)] complex allele, which represents an unusually high level of genetic homogeneity for ABCA4-related diseases. Causative ABCA4 mutations account for 79% of STGD and 31% of CRD cases. A combination of p.[(L541P; A1038V)] and/or a truncating ABCA4 mutation always resulted in an early disease onset. Identification of ABCA4 retinopathies provides a specific molecular diagnosis and justifies a prompt introduction of simple precautions that may slow disease progression. The comprehensive, population-specific study expands our knowledge on the genetic landscape of retinal diseases.

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7 [(R152*; V2050L)]. Login to comment
97 [(R152*; V2050L)] is a novel one. Login to comment
149 [(R152*; V2050L)] (8/184) (1/1172) p < 0.0001 c. Login to comment
172 [(R152*; V2050L)] was of immense importance for making a proper molecular diagnosis. Login to comment
173 A patient carrying exclusively p.R152* and p.V2050L, could have been easily misinterpreted as a compound heterozygote. Login to comment
174 Co-occurrence of p.R152* and p.V2050L has been previously noted in Polish patients (M. Krawczynski, unpublished data) and now the existence of the novel complex allele has been definitely confirmed. Login to comment