ABCMdb

ABCA4 p.Gly991Arg

ClinVar:	c.2971G>T , p.Gly991* ? , not provided c.2971G>C , p.Gly991Arg ? , not provided
Predicted by SNAP2:	A: N (53%), C: D (63%), D: D (66%), E: D (59%), F: D (95%), H: D (59%), I: D (75%), K: D (59%), L: D (75%), M: D (75%), N: N (53%), P: D (66%), Q: D (53%), R: D (95%), S: N (61%), T: N (53%), V: D (71%), W: D (91%), Y: D (80%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

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[hide] Stargardt macular dystrophy: common ABCA4 mutation... Mol Vis. 2012;18:280-9. Epub 2012 Feb 1. Roberts LJ, Nossek CA, Greenberg LJ, Ramesar RS
Stargardt macular dystrophy: common ABCA4 mutations in South Africa--establishment of a rapid genetic test and relating risk to patients.
Mol Vis. 2012;18:280-9. Epub 2012 Feb 1., [PMID:22328824]

Abstract [show]
PURPOSE: Based on the previous indications of founder ATP-binding cassette sub-family A member 4 gene (ABCA4) mutations in a South African subpopulation, the purpose was to devise a mechanism for identifying common disease-causing mutations in subjects with ABCA4-associated retinopathies (AARs). Facilitating patient access to this data and determining the frequencies of the mutations in the South African population would enhance the current molecular diagnostic service offered. METHODS: The majority of subjects in this study were of Caucasian ancestry and affected with Stargardt macular dystrophy. The initial cohort consisted of DNA samples from 181 patients, and was screened using the ABCR400 chip. An assay was then designed to screen a secondary cohort of 72 patients for seven of the most commonly occurring ABCA4 mutations in this population. A total of 269 control individuals were also screened for the seven ABCA4 mutations. RESULTS: Microarray screening results from a cohort of 181 patients affected with AARs revealed that seven ABCA4 mutations (p.Arg152*, c.768G>T, p.Arg602Trp, p.Gly863Ala, p.Cys1490Tyr, c.5461-10T>C, and p.Leu2027Phe) occurred at a relatively high frequency. The newly designed genetic assay identified two of the seven disease-associated mutations in 28/72 patients in a secondary patient cohort. In the control cohort, 12/269 individuals were found to be heterozygotes, resulting in an estimated background frequency of these mutations in this particular population of 4.46 per 100 individuals. CONCLUSIONS: The relatively high detection rate of seven ABCA4 mutations in the primary patient cohort led to the design and subsequent utility of a multiplex assay. This assay can be used as a viable screening tool and to reduce costs and laboratory time. The estimated background frequency of the seven ABCA4 mutations, together with the improved diagnostic service, could be used by counselors to facilitate clinical and genetic management of South African families with AARs.

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139 of alleles detected Frequency p.Cys54Tyr c. 161 G>A 2 0.55% p.Arg152* c. 454 C>T 12 3.31% p.Arg152Gln c. 455 G>A 3 0.83% p.Gly172Ser c. 514 G>A 1 0.28% p.Arg212Cys c. 634 C>T 1 0.28% p.Lys223Gln c. 667 A>C 1 0.28% p.V256V (Splice) c. 768 G>T 18 4.97% p.Pro291Leu c. 872 C>T 1 0.28% p.Trp439* c. 1317 G>A 1 0.28% p.Ala538Asp c. 1613 C>A 1 0.28% p.Leu541Pro c. 1622 T>C 1 0.28% p.Arg602Trp c. 1885C>T 30 8.29% p.Val643Met c. 1927 G>A 1 0.28% p.Arg653Cys c. 1957 C>T 1 0.28% p.Arg681* c. 2041 C>T 3 0.83% p.Val767Asp c. 2300 T>A 1 0.28% p.Trp855* c.2564_2571delGGTACCTT 2 0.55% p.Gly863Ala c. 2588 G>C 11 3.04% p.Val931Met c. 2791 G>A 1 0.28% p.Asn965Ser c. 2894 A>G 4 1.10% p.Val989Ala c. 2966 T>C 1 0.28% p.Gly991Arg c. 2971 G>C 1 0.28% p.Thr1019Met c. 3056 C>T 1 0.28% p.Ala1038Val c. 3113 C>T 3 0.83% p.Glu1087Lys c. 3259 G>A 1 0.28% p.Arg1108Cys c. 3322 C>T 2 0.55% p.Leu1201Arg c. 3602 T>G 4 1.10% p.Arg1300Gln c. 3899 G>A 4 1.10% p.Pro1380Leu c. 4139 C>T 3 0.83% p.Trp1408Arg c. 4222 T>C 1 0.28% - c. 4253+5G>A 1 0.28% p.Phe1440Ser c. 4319 T>C 1 0.28% p.Arg1443His c. 4328 G>A 1 0.28% p.Cys1490Tyr c.4469 G>A 54 14.92% p.Gln1513Pro fs*42 c. 4535 insC 1 0.28% p.Ala1598Asp c. 4793C>A 1 0.28% p.Arg1640Trp c. 4918 C>T 2 0.55% p.Ser1642Arg c. 4926 C>G 1 0.28% p.V1681_C1685del c. 5041 del15 1 0.28% - c. 5461-10T>C 24 6.63% - c. 5714+5 G>A 2 0.55% p.Pro1948Leu c. 5843 C>T 1 0.28% p.Gly1961Glu c. 5882 G>A 4 1.10% p.Leu2027Phe c.6079 C>T 30 8.29% p.Arg2030* c. 6088 C>T 1 0.28% p.Arg2030Gln c. 6089 G>A 3 0.83% p.Arg2038Trp c. 6112 C>T 1 0.28% p.Arg2107His c. 6320 G>A 2 0.55% p.Arg2118Glu fs*27 c. 6352 delA 1 0.28% p.Cys2150Tyr c. 6449 G>A 1 0.28% p.Gln2220* c. 6658 C>T 1 0.28% p.Gly863Ala mutation, which appears to have a founder effect in the Netherlands [13,15], the results obtained from the current study are in agreement with September et al.`s conclusions [9]. Login to comment

[hide] Association of a homozygous nonsense mutation in t... Ophthalmic Res. 2004 Mar-Apr;36(2):82-8. Simonelli F, Testa F, Zernant J, Nesti A, Rossi S, Rinaldi E, Allikmets R
Association of a homozygous nonsense mutation in the ABCA4 (ABCR) gene with cone-rod dystrophy phenotype in an Italian family.
Ophthalmic Res. 2004 Mar-Apr;36(2):82-8., [PMID:15017103]

Abstract [show]
Genetic variation in the ABCA4 (ABCR) gene has been associated with several distinct retinal phenotypes, including Stargardt disease/fundus flavimaculatus (STGD/FFM), cone-rod dystrophy (CRD), retinitis pigmentosa (RP) and age-related macular degeneration. The current model of genotype/phenotype association suggests that patients harboring deleterious mutations in both ABCR alleles would develop RP-like retinal pathology. Here we describe ABCA4-associated phenotypes, including a proband with a homozygous nonsense mutation in a family from Southern Italy. The proband had been originally diagnosed with STGD. Ophthalmologic examination included kinetic perimetry, electrophysiological studies and fluorescein angiography. DNA of the affected individual and family members was analyzed for variants in all 50 exons of the ABCA4 gene by screening on the ABCR400 microarray. A homozygous nonsense mutation 2971G>T (G991X) was detected in a patient initially diagnosed with STGD based on funduscopic evidence, including bull's eye depigmentation of the fovea and flecks at the posterior pole extending to the mid-peripheral retina. Since this novel nucleotide substitution results in a truncated, nonfunctional, ABCA4 protein, the patient was examined in-depth for the severity of the disease phenotype. Indeed, subsequent electrophysiological studies determined severely reduced cone amplitude as compared to the rod amplitude, suggesting the diagnosis of CRD. ABCR400 microarray is an efficient tool for determining causal genetic variation, including new mutations. A homozygous protein-truncating mutation in ABCA4 can cause a phenotype ranging from STGD to CRD as diagnosed at an early stage of the disease. Only a combination of comprehensive genotype/phenotype correlation studies will determine the proper diagnosis and prognosis of ABCA4-associated pathology.

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47 The previously described sequence change at this position was 2971G1C, a G991R missense mutation. Login to comment

[hide] Genotyping microarray (gene chip) for the ABCR (AB... Hum Mutat. 2003 Nov;22(5):395-403. Jaakson K, Zernant J, Kulm M, Hutchinson A, Tonisson N, Glavac D, Ravnik-Glavac M, Hawlina M, Meltzer MR, Caruso RC, Testa F, Maugeri A, Hoyng CB, Gouras P, Simonelli F, Lewis RA, Lupski JR, Cremers FP, Allikmets R
Genotyping microarray (gene chip) for the ABCR (ABCA4) gene.
Hum Mutat. 2003 Nov;22(5):395-403., [PMID:14517951]

Abstract [show]
Genetic variation in the ABCR (ABCA4) gene has been associated with five distinct retinal phenotypes, including Stargardt disease/fundus flavimaculatus (STGD/FFM), cone-rod dystrophy (CRD), and age-related macular degeneration (AMD). Comparative genetic analyses of ABCR variation and diagnostics have been complicated by substantial allelic heterogeneity and by differences in screening methods. To overcome these limitations, we designed a genotyping microarray (gene chip) for ABCR that includes all approximately 400 disease-associated and other variants currently described, enabling simultaneous detection of all known ABCR variants. The ABCR genotyping microarray (the ABCR400 chip) was constructed by the arrayed primer extension (APEX) technology. Each sequence change in ABCR was included on the chip by synthesis and application of sequence-specific oligonucleotides. We validated the chip by screening 136 confirmed STGD patients and 96 healthy controls, each of whom we had analyzed previously by single strand conformation polymorphism (SSCP) technology and/or heteroduplex analysis. The microarray was >98% effective in determining the existing genetic variation and was comparable to direct sequencing in that it yielded many sequence changes undetected by SSCP. In STGD patient cohorts, the efficiency of the array to detect disease-associated alleles was between 54% and 78%, depending on the ethnic composition and degree of clinical and molecular characterization of a cohort. In addition, chip analysis suggested a high carrier frequency (up to 1:10) of ABCR variants in the general population. The ABCR genotyping microarray is a robust, cost-effective, and comprehensive screening tool for variation in one gene in which mutations are responsible for a substantial fraction of retinal disease. The ABCR chip is a prototype for the next generation of screening and diagnostic tools in ophthalmic genetics, bridging clinical and scientific research.

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115 Mutations Detected in theTwoTest Populations by the ABCR400 Array,That Had Not Been Found by SSCP Number Nucleotide change Protein e¡ect Number of cases 1 161G4A C54Y 3 2 194G4A G65E 1 3 428C4T P143L 1 4 455G4A R152Q 1 5 514G4A G172S 1 6 635G4A R212H 1 7 656G4C R219T 1 8 768G4Ta Splice/V256V 3 9 1007C4G S336C 2 10 1268A4G H423R 4 11 1411G4A E471K 2 12 1622T4Ca L541P 8 13 1933G4A D645N 1 14 2041C4T R681X 5 15 2090G4A W697X 1 16 2471T4C I824T 1 17 2588G4Ca Splice/G863A 5 18 2828G4A R943Q 1 19 2966T4C V989A 1 20 2971G4C G991R 1 21 4139C4T P1380L 8 22 4195G4A E1399K 1 23 4328G4A R1443H 1 24 4457C4T P1486L 1 25 4462T4Ca C1488R 1 26 4469G4Aa C1490Y 1 27 4918C4Ta R1640W 2 28 IVS40+5G4A Splice 2 29 5537T4C I1846T 2 30 5882G4A G1961E 5 31 6089G4A R2030Q 1 32 6104T4C L2035P 1 33 6449G4A C2150Y 1 Mutation numbering is based on the cDNA sequence (GenBank NM_000350). Login to comment
195 The previously known sequence change at that position was 2971G>C (G991R). Login to comment

[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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62 Five of these ABCR mutations (1025-1038del14 bp, W339G, G991R, W1100X, and 6238-6239del2 bp) are novel, and the sixth mutation, I1562T, had been described previously only in AMD patients (Table 1; Allikmets et al. 1997a). Login to comment
65 Allele 1 nucleotide Amino acid Allele 2 Amino acid Age of change nucleotide change onset (years) AR129-08 37 AR140-01 6079C→T L2027F 3322C→T R1108C 36 AR204-04 35 AR280-03 6316C→T R2106C 6710insA T2237fs 35 AR311-04 4462T→C C1488R 35 AR336-03 2588G→C G863A 5898+1G→A E1966splice 39 AR343-06 2588G→C G863A 3322C→T R1108C 43 AR387-03 4919G→A R1640Q 2971G→C G991R 40 AR410-04 768G→T V256splice 3113C→T A1038V 38 AR440-03 6238-6239del2 bp S2080fs 44 AR448-01a 454C→T R152X 6089G→A R2030Q 52 AR452-04 2005-2006del2 bp M669fs 6089G→A R2030Q 40 AR455-05 [1622T→C;3113C→T] [L541P;A1038V] 43 AR474-02 36 AR516-01a 5196+1G→A I1732splice 3113C→T A1038V 47 AR518-03 3322C→T R1108C 35 AR540-01a 4685T→C I1562T 51 AR594-02a 5196+1G→A I1732splice 36 AR606-04 3322C→T R1108C 2588G→C G863A 39 AR608-02 1025-1038del14 bp D342fs 40 AR617-03 2827C→T R943W 39 AR632-02a 3386G→T R1129L 50 AR649-03 3303G→A W1101X 3113C→T A1038V 36 AR662-02a 1015T→G W339G 50 AR723-01a 3602T→G L1201R 65 Fig.1 Pedigrees of late-onset Stargardt disease families (filled symbols STGD1-affected individuals). Login to comment
70 Furthermore, three of these alterations (W339G, G991R, and 6238-6239del2 bp) segregated with multiple STGD1 affecteds within the family; families with the alterations 1025-1038del14 bp, W1101X, and I1562T had only single affecteds and were uninformative for segregation. Login to comment

[hide] Detection rate of pathogenic mutations in ABCA4 us... Arch Ophthalmol. 2012 Nov;130(11):1486-90. doi: 10.1001/archophthalmol.2012.1697. Downes SM, Packham E, Cranston T, Clouston P, Seller A, Nemeth AH
Detection rate of pathogenic mutations in ABCA4 using direct sequencing: clinical and research implications.
Arch Ophthalmol. 2012 Nov;130(11):1486-90. doi: 10.1001/archophthalmol.2012.1697., [PMID:23143460]

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28 In 5 of the 11 patients, the identification of 2 pathogenic mutations confirmed the historical diagnosis and all had chorioretinal atro- Table. Results From Direct Sequencing of the ABCA4 Gene in 50 Patients Subject No. Change 1 Change 2 Phase Segregation Age at Onset, y Phenotype Grade, Macula Flecks/ Cones/Rodsa Additional Variants Conclusion Nucleotide Amino Acid Nucleotide Amino Acid 1 1Ab0e;G M1V 2588Gb0e;C G863A In trans Unaffected parents carriers 30 STGD maf9;/0/0 R2030Q 3 PVs 2 161Gb0e;A C54Y 2588Gb0e;C G863A In trans Affected sibling with same mutations 12 STGD m/0/0 0 2 PVs 3 161Gb0e;A C54Y 5882Gb0e;A G1961E NK NK 18 STGD m/0/0 0 2 PVs 4 634Cb0e;T R212C 4457Cb0e;T P1486L In trans Unaffected parents carriers 17 STGD m/0/0 0 2 PVs 5 2588Gb0e;C G863A 4469Gb0e;A C1490Y NK NK 48 STGD maf9;/0/1 0 2 PVs 6 2971Gb0e;C G991R 4254-2Ab0e;G Splice NK NK 21 STGD m/0/0 0 2 PVs 7 2971Gb0e;C G991R 3602Tb0e;G L1201R NK NK 18 STGD maf9;af9;/NP/NP V643M (likely), G885E (likely), G1441D (unlikely), V2244V (highly likely) b0e;2 PVs 8 3322Cb0e;T R1108C 768Gb0e;T V256V NK NK 13 STGD maf9;af9;/1/1 0 2 PVs 9 3322Cb0e;T R1108C 6079Cb0e;T L2027F NK NK 26 STGD maf9;/0/0 0 2 PVs 10 3386Gb0e;T R1129L 4469Gb0e;A C1490Y In trans Unaffected parents carriers 15 STGD maf9;/0/0 R152Q (unlikely) 2 PVs (continued) ARCH OPHTHALMOL/VOL 130 (NO. 11), NOV 2012 WWW.ARCHOPHTHALMOL.COM 1486 phy on current clinical examination, consistent with progression of the disorder.5 One of the 11 patients with chorioretinal atrophy (subject 40) had a single stop codon, again strongly supporting the original clinical diagnosis. Six of the 11 patients did not have pathogenic mutations in ABCA4. 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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141 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) Exon Nucleotide Substitution and Amino Acid Change Number of Alleles Allele Frequency 2 c.71G>A, p.Arg24His 1 0.36% 2 c.161G>A, p.Cys54Tyr 3 1.07% 3 c.223T>G, p.Cys75Gly 1 0.36% 5 c.455G>A, p.Arg152Gln 1 0.36% 5 c.454C>T, p.Arg152* 1 0.36% 5 c.466 A>G, p.Ile156Val 2 0.71% 6 c.634C>T, p. Arg212Cys 3 1.07% 6 c.656G>C, p.Arg219Thr 1 0.36% 6 c.666_678delAAAGACGGTGCGC, p.Lys223_Arg226delfs 2 0.71% 6 c.768G>T, Splicing site 4 1.42% 8 c.1037A>C, p.Lys346Thr 1 0.36% 10 c.1222C>T, p.Arg408* 3 1.07% 12 c.1622T>C, p.Leu541Pro 2 0.71% 12 c.1648 G>T, p.Gly550* 1 0.36% 13 c.1804C>T, p.Arg602Trp 1 0.36% 13 c.1817G>A, p.Gly606Asp 1 0.36% 13 c.1922G>C, p.Cys641Ser 1 0.36% Int 13 c.1937&#fe;1G>A, Splicing site 2 0.71% 14 c.1957C>T, p.Arg653Cys 2 0.71% 17 c.2588G>C, p.Gly863Ala 19 6.79% 18 c.2701A>G, p.Thr901Ala 1 0.36% 19 c.2791G>A, p.Val931Met 2 0.71% 19 c.2894A>G, p.Asn965Ser 1 0.36% 20 c.2966T>C, p.Vla989Ala 3 1.07% 20 c.2971G>C, p.Gly991Arg 2 0.71% 21 c.3056C>T, p.Thr1019Met 1 0.36% 21 c.3113C>T, p.Ala1038Val 3 1.07% 21 c.3064G>A, p.Glu1022Lys 2 0.71% 22 c.3211_3212insGT, p.Ser1071Cysfs 6 2.14% 22 c.3259G>A, p.Glu1087Lys 4 1.43% 22 c.3292C>T, p.Arg1098Cys 1 0.36% 22 c.3322C>T, p.Arg1108Cys 5 1.79% 22 c.3323G>A, p.Arg1108His 1 0.36% 23 c.3364G>A, p.Glu1122Lys 1 0.36% 23 c.3386G>A, p.Arg1129His 1 0.36% 24 c.3602T>G, p.Leu1201Arg 3 1.07% 27 c.3898C>T, p.Arg1300* 2 0.71% 28 c.4139C>T, p.Pro1380Leu 14 5.00% 28 c.4222T>C, p.Trp1408Arg 1 0.36% 28 c.4234C>T, p.Gly1412* 1 0.36% 28 c.4253&#fe;5G>T, Splice site 1 0.36% 28 c.4253&#fe;4C>T, Splice site 1 0.36% 29 c.4283C>T, p.Thr1428Met 1 0.36% 29 c.4319T>C, p.Phe1440Ser 1 0.36% 29 c.4462T>C, p.Cys1488Arg 1 0.36% 30 c.4469G>A, p.Cys1490Tyr 5 1.79% 30 c.4537_4538insC, p.Gly1513Profs 1 0.36% 31 c.4577C>T, p.Thr1526Met 2 0.71% 33 c.4715C>T, p.Thr1572Met 1 0.36% Continued on next page TABLE 3. Login to comment

[hide] ABCA4 gene screening by next-generation sequencing... Invest Ophthalmol Vis Sci. 2013 Oct 11;54(10):6662-74. doi: 10.1167/iovs.13-12570. Fujinami K, Zernant J, Chana RK, Wright GA, Tsunoda K, Ozawa Y, Tsubota K, Webster AR, Moore AT, Allikmets R, Michaelides M
ABCA4 gene screening by next-generation sequencing in a British cohort.
Invest Ophthalmol Vis Sci. 2013 Oct 11;54(10):6662-74. doi: 10.1167/iovs.13-12570., [PMID:23982839]

Abstract [show]
PURPOSE: We applied a recently reported next-generation sequencing (NGS) strategy for screening the ABCA4 gene in a British cohort with ABCA4-associated disease and report novel mutations. METHODS: We identified 79 patients with a clinical diagnosis of ABCA4-associated disease who had a single variant identified by the ABCA4 microarray. Comprehensive phenotypic data were obtained, and the NGS strategy was applied to identify the second allele by means of sequencing the entire coding region and adjacent intronic sequences of the ABCA4 gene. Identified variants were confirmed by Sanger sequencing and assessed for pathogenicity by in silico analysis. RESULTS: Of the 42 variants detected by prescreening with the microarray, in silico analysis suggested that 34, found in 66 subjects, were disease-causing and 8, found in 13 subjects, were benign variants. We detected 42 variants by NGS, of which 39 were classified as disease-causing. Of these 39 variants, 31 were novel, including 16 missense, 7 splice-site-altering, 4 nonsense, 1 in-frame deletion, and 3 frameshift variants. Two or more disease-causing variants were confirmed in 37 (47%) of 79 patients, one disease-causing variant in 36 (46%) subjects, and no disease-causing variant in 6 (7%) individuals. CONCLUSIONS: Application of the NGS platform for ABCA4 screening enabled detection of the second disease-associated allele in approximately half of the patients in a British cohort where one mutation had been detected with the arrayed primer extension (APEX) array. The time- and cost-efficient NGS strategy is useful in screening large cohorts, which will be increasingly valuable with the advent of ABCA4-directed therapies.

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56 40 c.4926C>G p.S1642R DC c.5041_5055del GTGGTTGCCATCTGC p.V1681_C1685del DC 2 41 c.4956T>G p.Y1652* DC 1 42 c.5018&#fe;2T>C Splice site DC 1 43 c.5461-10T>C DC c.6385A>G p.S2129G PDC 2 44 c.5461-10T>C DC 1 45 c.5461-10T>C DC 1 46 c.5461-10T>C DC 1 47 c.5461-10T>C DC 1 48 c.5461-10T>C DC 1 49 c.5461-10T>C DC 1 50 c.5461-10T>C DC 1 51 c.5585-1G>A Splice site DC 1 52 c.5714&#fe;5G>A Splice site DC c.6209C>G p.T2070R DC 2 53 c.5882G>A p.G1961E DC c.2686A>G p.K896E B 1 54 c.5882G>A p.G1961E DC c.3050&#fe;1G>C Splice site DC 2 55 c.5882G>A p.G1961E DC c.3392delC/3393C>G p.A1131Gfs DC 2 56 c.5882G>A p.G1961E DC c.4539&#fe;2T>G Splice site DC 2 57 c.5882G>A p.G1961E DC c.4552A>C p.S1518R DC 2 58 c.5882G>A p.G1961E DC c.5899-2delA Splice site DC 2 59 c.5882G>A p.G1961E DC 1 60 c.6079C>T p.L2027F DC c.1906C>T p.Q636* DC 2 61 c.6079C>T p.L2027F DC c.3322C>T p.R1108C DC 2 Allele 2 (p.R1108C) was APEX-false-negative 62 c.6079C>T p.L2027F DC c.3370G>T p.D1124Y DC 2 63 c.6079C>T p.L2027F DC 1 64 c.6089G>A p.R2030Q DC c.4326C>A p.N1442K DC 2 65 c.6445C>T p.R2149* DC 1 66 c.6709A>C p.T2237P DC c.5899-3_5899-2delTA Splice site DC 2 67 c.2971G>C p.G991R B c.4538A>G p.Q1513R DC 1 68 c.3602T>G p.L1201R B c.1749G>C p.K583N DC 1 69 c.3602T>G p.L1201R B c.1982_1983insG p.A662fs DC 1 70 c.3602T>G p.L1201R B c.2972G>T p.G991V DC 1 71 c.4685T>C p.I1562T B c.3289A>T p.R1097* DC 1 72 c.6320G>A p.R2107H B c.2510T>C p.L837P DC 1 73 c.6320G>A p.R2107H B c.4352&#fe;1G>A Splice site DC 1 74 c.2701A>G p.T901A B 0 75 c.3602T>G p.L1201R B 0 76 c.4283C>T p.T1428M B 0 77 c.466A>G p.I156V B 0 78 c.466A>G p.I156V B 0 79 c.4715C>T p.T1572M B 0 Putative novel variants are shown in italics. Login to comment
62 Hum Var Score (0-1) Site Wt CV Mt CV CV % Variation 3 c.161G>A p.C54Y 1 1 [ [ Lewis RA, et al. 11 Tol. 0.11 PRD 0.994 No change 1/13006 db SNP (rs150774447) 3 c.223T>G p.C75G 1 2 [ [ Lewis RA, et al. 11 Del. NA POD 0.603 No change ND 5 c.466A>G p.I156V 2 77, 78 [ [ Papaioannou M, et al. 16 Tol. 0.46 B 0.003 No change 16/13006 db SNP (rs112467008) Benign 6 c.655A>T p.R219* 1 11 [ Xi Q, et al. 27 ND 6 c.740A>C p.N247T 1 3 [ [ APEX Del. NA B 0.135 No change ND 6 c.768G>T Splice site 1 4 [ [ Klevering BJ, et al. 22 Tol. 0.56 NA Don. 70.4 58 Site broken (17.51) ND 9 c.1222C>T p.R408* 1 5 [ [ Webster AR, et al. 7 ND 12 c.1726G>C p.D576H 1 36 [ Downs K, et al. 25 POD 0.688 Acc. 68.1 39.1 Site broken (42.54) 1/13006 13 c.1804C>T p.R602W 1 6 [ [ Lewis RA, et al. 11 Del. 0.00 B 0.129 No change ND db SNP (rs 6179409) 13 c.1805G>A p.R602Q 1 7 [ [ Webster AR, et al. 7 Del. 0.04 PRD 0.513 Acc. 48.9 77.9 New site (&#fe;59.14) 2/13006 db SNP (rs61749410) 13 c.1906C>T p.Q636* 3 12, 13, 60 [ Zernant J, et al. 5 No change 1/13006 db SNP (rs145961131) 13 c.1922G>C p.C641S 1 8 [ [ Stenirri S, et al. 24 Del. 0.00 No change ND db SNP (rs61749416) 14 c.1957C>T p.R653C 2 9, 10 [ [ Rivera A, et al. 17 Del. 0.00 PRD 0.999 No change ND db SNP (rs61749420) 17 c.2588G>C p.G863A/ p.DelG863 5 11, 12, 13, 14, 15 [ [ Lewis RA, et al. 11 / Maugeri A, et al. 29 Del. 0.00 PRD 0.996 No change 68/13006 db SNP (rs76157638) 18 c.2701A>G p.T901A 1 74 [ [ APEX Tol. 0.82 B 0.008 23/13006 db SNP (rs139655975) Benign 19 c.2894A>G p.N965S 1 16 [ [ Lewis RA, et al. 11 Del. 0.03 PRD 0.981 Acc. 53.4 82.3 New site (&#fe;54.26) ND db SNP (rs201471607) 20 c.2971G>C p.G991R 1 67 [ [ Yatsenko AN, et al. 13 Del. 0.02 PRD 0.999 No change 28/13006 db SNP (rs147484266) Benign 22 c.3064G>A p.E1022K 2 17, 18 [ [ Webster AR, et al. 7 Del. 0.00 PRD 1.000 No change ND db SNP (rs61749459) 22 c.3208_3209insGT p.S1071fs 5 19, 20, 21, 22, 25 [ [ APEX ND False-negative in APEX in patient 25 22 c.3292C>T p.R1098C 1 23 [ [ Rivera A, et al. 17 Del. NA PRD 0.999 No change ND 22 c.3322C>T p.R1108C 3 16, 24, 61 [ [ Rozet JM, et al. 10 Del. 0.00 PRD 0.986 No change 1/13006 db SNP (rs61750120) False-negative in APEX in patients 16 and 61 23 c.3386G>A p.R1129H 1 25 [ Zernant J, et al. 5 PRD 0.989 No change ND False-negative in NGS in patient 25 24 c.3602T>G p.L1201R 4 72, 73, 74, 79 [ [ Lewis RA, et al. 11 Tol. 0.37 B 0.052 Don. 61.3 73.7 New site (20.08) 416/13006 db SNP (rs61750126) Benign 28 c.4139C>T p.P1380L 7 30, 31, 32, 33, 34, 35, 36 [ [ Lewis RA, et al. 11 Del. 0.01 B 0.377 No change 2/13006 db SNP (rs61750130) 28 c.4234C>T p.Q1412* 1 33 [ [ Rivera A, et al. 17 ND db SNP (rs61750137) 29 c.4283C>T p.T1428M 1 76 [ [ APEX Tol. 0.15 B 0.010 No change 2/13006 db SNP (rs1800549) Benign 29 c.4319T>C p.F1440S 1 34 [ [ Lewis RA, et al. 11 Del. 0.00 POD 0.744 No change ND dbSNP (rs61750141) 29 c.4326C>A p.N1442K 1 64 [ Zernant J, et al. 5 Tol. NA POD 0.374 No change ND 29 c.4328G>A p.R1443H 1 35 [ [ Rivera A, et al. 17 Del. 0.02 PRD 0.999 No change 1/13006 dbSNP (rs61750142) IVS29 c.4352&#fe;1G>A Splice site 1 73 [ Zernant J, et al. 5 Don. 82.3 55.4 WT site broken (32.62) ND 30 c.4469G>A p.C1490Y 2 36, 37 [ [ Lewis RA, et al. 11 Del. 0.00 PRD 0.994 No change ND dbSNP (rs61751402) 30 c.4538A>G p.Q1513R 1 67 [ Webster AR, et al. 7 Tol. NA Benign 0.043 Acc. 91.7 62.8 Site broken (31.55) ND T ABLE 3. Continued Exon/ IVS Nucleotide Substitution Protein Change/ Effect N of Alleles Identified Pt Method Previous Report SIFT Polyphen 2 HSF Matrix Allele Freq. by EVS Reference Comment APEX NGS Pred. Tol. Index (0-1) Pred. Login to comment

[hide] Quantitative fundus autofluorescence distinguishes... Ophthalmology. 2015 Feb;122(2):345-55. doi: 10.1016/j.ophtha.2014.08.017. Epub 2014 Oct 3. Duncker T, Tsang SH, Lee W, Zernant J, Allikmets R, Delori FC, Sparrow JR
Quantitative fundus autofluorescence distinguishes ABCA4-associated and non-ABCA4-associated bull's-eye maculopathy.
Ophthalmology. 2015 Feb;122(2):345-55. doi: 10.1016/j.ophtha.2014.08.017. Epub 2014 Oct 3., [PMID:25283059]

Abstract [show]
PURPOSE: Quantitative fundus autofluorescence (qAF) and spectral-domain optical coherence tomography (SD OCT) were performed in patients with bull's-eye maculopathy (BEM) to identify phenotypic markers that can aid in the differentiation of ABCA4-associated and non-ABCA4-associated disease. DESIGN: Prospective cross-sectional study at an academic referral center. SUBJECTS: Thirty-seven BEM patients (age range, 8-60 years) were studied. All patients exhibited a localized macular lesion exhibiting a smooth contour and qualitatively normal-appearing surrounding retina without flecks. Control values consisted of previously published data from 277 healthy subjects (374 eyes; age range, 5-60 years) without a family history of retinal dystrophy. METHODS: Autofluorescence (AF) images (30 degrees , 488-nm excitation) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference to account for variable laser power and detector sensitivity. The grey levels (GLs) from 8 circularly arranged segments positioned at an eccentricity of approximately 7 degrees to 9 degrees in each image were calibrated to the reference (0 GL), magnification, and normative optical media density to yield qAF. In addition, horizontal SD OCT images through the fovea were obtained. All patients were screened for ABCA4 mutations using the ABCR600 microarray, next-generation sequencing, or both. MAIN OUTCOME MEASURES: Quantitative AF, correlations between AF and SD OCT, and genotyping for ABCA4 variants. RESULTS: ABCA4 mutations were identified in 22 patients, who tended to be younger (mean age, 21.9+/-8.3 years) than patients without ABCA4 mutations (mean age, 42.1+/-14.9 years). Whereas phenotypic differences were not obvious on the basis of qualitative fundus AF and SD OCT imaging, with qAF, the 2 groups of patients were clearly distinguishable. In the ABCA4-positive group, 37 of 41 eyes (19 of 22 patients) had qAF8 of more than the 95% confidence interval for age. Conversely, in the ABCA4-negative group, 22 of 26 eyes (13 of 15 patients) had qAF8 within the normal range. CONCLUSIONS: The qAF method can differentiate between ABCA4-associated and non-ABCA4-associated BEM and may guide clinical diagnosis and genetic testing.

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66 [L541P; A1038V] 438 432 16 M 25 White 0.60 0.60 p.S84fs p.R2107H 294 17 F 24 Black 0.70 0.88 p.G991R p.L1138P 321 326 18 M 26 White 0.00y 0.00y p.R1300* p.R2106C 419 412 19 M 11 White 0.40z 0.40z p.W821R p.C2150Y 304 296 20 F 16 White 0.70 0.40 p.K1547* p.R2030Q 481 513 21 F 13 White 1.30 1.00 pR1108C p.Q1412* 511 528 22 F 18 White 0.00 0.00 p.G863A c.5898&#fe;1G/A 465 431 Mutations in Other Genes 23 F 16 White 0.40 0.48 GUCY2D e p.R838H 152 165 24 M 53 Black 0.88 0.88 CNGA3 e p. Login to comment

[hide] Flecks in Recessive Stargardt Disease: Short-Wavel... Invest Ophthalmol Vis Sci. 2015 Jul;56(8):5029-39. doi: 10.1167/iovs.15-16763. Sparrow JR, Marsiglia M, Allikmets R, Tsang S, Lee W, Duncker T, Zernant J
Flecks in Recessive Stargardt Disease: Short-Wavelength Autofluorescence, Near-Infrared Autofluorescence, and Optical Coherence Tomography.
Invest Ophthalmol Vis Sci. 2015 Jul;56(8):5029-39. doi: 10.1167/iovs.15-16763., [PMID:26230768]

Abstract [show]
PURPOSE: We evaluated the incongruous observation whereby flecks in recessive Stargardt disease (STGD1) can exhibit increased short-wavelength autofluorescence (SW-AF) that originates from retinal pigment epithelium (RPE) lipofuscin, while near-infrared AF (NIR-AF), emitted primarily from RPE melanin, is usually reduced or absent at fleck positions. METHODS: Flecks in SW- and NIR-AF images and spectral-domain optical coherence tomography (SD-OCT) scans were studied in 19 STGD1 patients carrying disease-causing ABCA4 mutations. Fleck spatial distribution and progression were recorded in serial AF images. RESULTS: Flecks observed in SW-AF images typically colocalized with darkened foci in NIR-AF images; the NIR-AF profiles were larger. The decreased NIR-AF signal from flecks preceded apparent changes in SW-AF. Spatiotemporal changes in fleck distribution usually progressed centrifugally, but in one case centripetal expansion was observed. Flecks in SW-AF images corresponded to hyperreflective deposits that progressively traversed photoreceptor-attributable bands in SD-OCT images. Outer nuclear layer (ONL) thickness negatively correlated with expansion of flecks from outer to inner retina. CONCLUSIONS: In the healthy retina, RPE lipofuscin fluorophores form in photoreceptor cells but are transferred to RPE; thus the SW-AF signal from photoreceptor cells is negligible. In STGD1, NIR-AF imaging reveals that flecks are predominantly hypofluorescent and larger and that NIR-AF darkening occurs prior to heightened SW-AF signal. These observations indicate that RPE cells associated with flecks in STGD1 are considerably changed or lost. Spectral-domain OCT findings are indicative of ongoing photoreceptor cell degeneration. The bright SW-AF signal of flecks likely originates from augmented lipofuscin formation in degenerating photoreceptor cells impaired by the failure of RPE.

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50 [3050&#fe;5G>A]; p. [G1961E] 15 M 48.36 African American 0 0 p. [G991R]; c. Login to comment