ABCMdb

ABCA4 p.Gln1412*

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[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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55 1 c.161G>A p.C54Y DC c.2297G>T p.G766V DC 2 2 c.223T>G p.C75G DC c.5088C>G p.S1696R DC 2 3 c.740A>C p.N247T DC c.1433T>C p.I478T B c.2345G>A p.W782* DC 2 4 c.768G>T Splice site DC 1 5 c.1222C>T p.R408* DC c.2568C>A p.Y856* DC 2 6 c.1804C>T p.R602W DC c.859-9T>C Splice site PDC 2 7 c.1805G>A p.R602Q DC c.5113C>T p.R1705W DC 2 8 c.1922G>C p.C641S DC 1 9 c.1957C>T p.R653C DC 1 10 c.1957C>T p.R653C DC 1 11 c.2588G>C p.G863A DC c.655A>T p.R219* DC 2 Allele 2 (p.R219*) was APEX-false-negative 12 c.2588G>C p.G863A DC c.1906C>T p.Q636* DC 2 13 c.2588G>C p.G863A DC c.1906C>T p.Q636* DC 2 14 c.2588G>C p.G863A DC 1 15 c.2588G>C p.G863A DC 1 16 c.2894A>G p.N965S DC c.3322C>T p.R1108C DC 2 Allele 2 (p.R1108C) was APEX-false-negative 17 c.3064G>A p.E1022K DC c.6729&#fe;4_&#fe;18delAGTTGGCCCTGGGGC Splice site DC 2 18 c.3064G>A p.E1022K DC 1 19 c.3208_3209insGT p.S1071fs DC c.2942C>T p.P981L DC c.6529G>A p.D2177N B 2 20 c.3208_3209insGT p.S1071fs DC c.1519G>T p.D507Y DC 2 21 c.3208_3209insGT p.S1071fs DC c.4634G>A p.S1545N DC 2 22 c.3208_3209insGT p.S1071fs DC 1 23 c.3292C>T p.R1098C DC c.3299T>A p.I1100N DC 2 24 c.3322C>T p.R1108C DC c.4978delC p.L1661* DC 2 25 c.3386G>A p.R1129H DC c.3208_3209insGT p.S1071fs DC c.4634G>A p.S1545N DC 3 Allele 2 (p.S1071fs) was APEX false-negative and allele 1 (p.R1129H) was NGS false-negative 26 c.4139C>T p.P1380L DC c.3191-1G>T Splice site DC 2 27 c.4139C>T p.P1380L DC c.3398T>C p.I1133T PDC 2 28 c.4139C>T p.P1380L DC c.4070C>A p.A1357E DC 2 29 c.4139C>T p.P1380L DC c.4773G>C Splice site DC 2 30 c.4139C>T p.P1380L DC 1 31 c.4139C>T p.P1380L DC 1 32 c.4139C>T p.P1380L DC 1 33 c.4234C>T p.Q1412* DC 1 34 c.4319T>C p.F1440S DC 1 35 c.4328G>A p.R1443H DC c.180delG p.M61fs DC 2 36 c.4469G>A p.C1490Y DC c.1726G>C p.D576H DC 2 37 c.4469G>A p.C1490Y DC 1 38 c.4537_4538insC p.Q1513fs DC c.5578C>T p.R1860W DC 2 Allele 1 (p.Q1513fs) was NGS-false-negative 39 c.4577C>T p.T1526M DC 1 T ABLE 2. Continued Pt Allele 1 Detected by APEX Allele 2 Detected by NGS Allele 3 Detected by NGS Total N of DC Variants Comments DNA Change Protein Change/ Effect Pred. Patho. DNA Change Protein Change/ Effect Pred. Patho. DNA Change Protein Change/ Effect Pred. Patho. 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 in recessive ... Invest Ophthalmol Vis Sci. 2014 May 1;55(5):2841-52. doi: 10.1167/iovs.13-13624. Burke TR, Duncker T, Woods RL, Greenberg JP, Zernant J, Tsang SH, Smith RT, Allikmets R, Sparrow JR, Delori FC
Quantitative fundus autofluorescence in recessive Stargardt disease.
Invest Ophthalmol Vis Sci. 2014 May 1;55(5):2841-52. doi: 10.1167/iovs.13-13624., [PMID:24677105]

Abstract [show]
PURPOSE: To quantify fundus autofluorescence (qAF) in patients with recessive Stargardt disease (STGD1). METHODS: A total of 42 STGD1 patients (ages: 7-52 years) with at least one confirmed disease-associated ABCA4 mutation were studied. Fundus AF images (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 gray levels (GLs) of each image were calibrated to the reference, zero GL, magnification, and normative optical media density to yield qAF. Texture factor (TF) was calculated to characterize inhomogeneities in the AF image and patients were assigned to the phenotypes of Fishman I through III. RESULTS: Quantified fundus autofluorescence in 36 of 42 patients and TF in 27 of 42 patients were above normal limits for age. Young patients exhibited the relatively highest qAF, with levels up to 8-fold higher than healthy eyes. Quantified fundus autofluorescence and TF were higher in Fishman II and III than Fishman I, who had higher qAF and TF than healthy eyes. Patients carrying the G1916E mutation had lower qAF and TF than most other patients, even in the presence of a second allele associated with severe disease. CONCLUSIONS: Quantified fundus autofluorescence is an indirect approach to measuring RPE lipofuscin in vivo. We report that ABCA4 mutations cause significantly elevated qAF, consistent with previous reports indicating that increased RPE lipofuscin is a hallmark of STGD1. Even when qualitative differences in fundus AF images are not evident, qAF can elucidate phenotypic variation. Quantified fundus autofluorescence will serve to establish genotype-phenotype correlations and as an outcome measure in clinical trials.

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No. Sentence Comment
85 [L541P; A1038V]; p.L2027F 733 749 3.9 4.0 36 F 20 7 0.88 1.00 II II p.R1640W 571 552 3.4 3.8 37 F 12 3 0.80 0.80 I I p.R1108C; p.Q1412* 536 501 1.7 1.7 * All subjects were white, except for patients 10, 22, and 36 who were Indian, Hispanic, and black, respectively. Login to comment

[hide] Generalized choriocapillaris dystrophy, a distinct... Invest Ophthalmol Vis Sci. 2014 Apr 29;55(4):2766-76. doi: 10.1167/iovs.13-13391. Bertelsen M, Zernant J, Larsen M, Duno M, Allikmets R, Rosenberg T
Generalized choriocapillaris dystrophy, a distinct phenotype in the spectrum of ABCA4-associated retinopathies.
Invest Ophthalmol Vis Sci. 2014 Apr 29;55(4):2766-76. doi: 10.1167/iovs.13-13391., [PMID:24713488]

Abstract [show]
PURPOSE: We describe a particular form of autosomal recessive generalized choriocapillaris dystrophy phenotype associated with ABCA4 mutations. METHODS: A cohort of 30 patients with identified ABCA4 mutations and a distinct phenotype was studied. A retrospective review of history, fundus photographs, electroretinography, visual field testing, dark adaptometry, and optical coherence tomography was performed. Genetic analyses were performed by ABCA4 microarray analysis, high resolution melting, and/or next generation sequencing of all protein-coding sequences of the ABCA4 gene. RESULTS: The earliest recorded manifestation of ABCA4-associated disease was a central bull's eye type of macular dystrophy that progressed to chorioretinal atrophy of the macula with coarse rounded hyperpigmentations and expanding involvement of the periphery. The mean age at first presentation was 10.3 years, the longest follow-up was 61 years. All patients had two ABCA4 mutations identified, confirming the molecular genetic diagnosis of an ABCA4-associated disease. Most patients harbored at least one mutation classified as "severe," the most common of which was the p.N965S variant that had been found previously at a high frequency among patients with ABCA4-associated retinal dystrophies in Denmark. CONCLUSIONS: Generalized choriocapillaris dystrophy is a progressive ABCA4-associated phenotype characterized by early-onset macular dystrophy that disperses and expands to widespread end-stage chorioretinal atrophy with profound visual loss. All cases in this study were confirmed as harboring two ABCA4 mutations. Most of the ABCA4 mutations were classified as "severe" explaining the early onset, panretinal degeneration, and fast progression of the disease.

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114 Two ABCA4 mutations were detected in patient D109 from generation III; a common Danish missense mutation p.N965S and a nonsense mutation p.Q1412*. Login to comment
115 In the fourth generation, the array screening identified only the p.Q1412* mutation, which was presumably inherited from the unaffected father. Login to comment
123 Summary of Detected Potential Pathogenic Variants (Known and Novel [in Bold Face]) Found in the ABCA4 Gene of Patients With Generalized Choriocapillaris Dystrophy Patient Method Mutation 1 Mutation 2 Nucleotide Protein Nucleotide Protein D513 NGS c.203C>T p.P68L c.2894A>G p.N965S D514 Microarray, NGS c.2894A>G p.N965S c.5461-10T>C - D516 NGS c.4926C>G p.S1642R c.5041_5055del p.V1681_C1685del D517 NGS c.5169C>G p.Y1723* c.6079C>T p.L2027F D137 Microarray, NGS c.2894A>G p.N965S c.2894A>G p.N965S D801 Microarray, NGS c.6386&#fe;1G>A Aberrant splicing c.4234C>T p.Q1412* D109 Microarray c.2894A>G p.N965S c.4234C>T p.Q1412* D040 Microarray c.6229C>T p.R2077W c.6229C>T p.R2077W D159 Microarray c.3113C>T p.L541P/A1038V c.3113C>T p.L541P/A1038V D129 Microarray c.2894A>G p.N965S c.3322C>T p.R1108C D115 Microarray c.2894A>G p.N965S c.3113C>T p.L541P/A1038V D033 Microarray c.2894A>G p.N965S c.2041C>T p.R681* D023 Microarray c.203C>T p.P68L c.3329-2A>G Aberrant splicing D001 Microarray c.666_678del p.K223_R226delfs c.4667&#fe;2T>C Aberrant splicing D147 Microarray, HRM c.2894A>G p.N965S c.2408delG p.G803fs D162 Microarray c.3329-2A>G Aberrant splicing c.6089G>A p.R2030Q D022 Microarray, HRM c.4462T>C p.C1488R c.4102C>T p.R1368C D112 Microarray, HRM c.2894A>G p.N965S c.1529T>G p.L510R D108 Microarray, HRM c.1648G>A p.G550R c.4102C>T p.R1368C D107 Microarray c.666_678del p.K223_R226delfs c.2588G>C p.G863A D070 Microarray c.2588G>C p.G863A c.2588G>C p.G863A D116 Microarray c.2300T>A p.V767D c.5461-10T>C - D135 Microarray, HRM c.2894A>G p.N965S c.2408delG p.G803fs D117 Microarray, HRM c.3191-2A>G Aberrant splicing c.2408delG p.G803fs D186 Microarray, HRM c.3322C>T p.R1108C c.6386&#fe;1G>A Aberrant splicing D173 Microarray, HRM c.4469G>A p.C1490Y c.2915C>A p.T972N TABLE 3. Login to comment
124 In Silico Analysis of ABCA4 Variants Detected in This Study Using Alamut 2.2 Software cDNA Variant Protein Variant Effect on Protein Function AGVGD Class SIFT Prediction Effect on Protein PPH2 Prediction Effect on Protein TASTER Prediction Effect on Splicing Missense variants c.203C>T p.P68L C65 Deleterious Probably damaging Disease causing c.1529T>G p.L510R C65 Deleterious Benign Polymorphism c.1622T>C p.L541P Reduced ATP binding mislocali- zation26,27 C65 Deleterious Probably damaging Disease causing c.1648G>A p.G550R C65 Deleterious Possibly damaging Disease causing New acceptor site c.2300T>A p.V767D Reduced protein28 C65 Deleterious Benign Disease causing c.2588G>C p.G863A Reduced protein level, reduced ATP binding, reduced ATPase activity26 C55 Deleterious Possibly damaging Disease causing Predicted change at acceptor site 1 bp upstream: 11.1%, creating a new stronger acceptor 3 bp downstream c.2894A>G p.N965S Reduced ATP binding26 C45 Deleterious Probably damaging Disease causing New acceptor site c.2915C>A p.T972N C55 Deleterious Probably damaging Disease causing c.3113C>T p.A1038V Reduced ATP binding, reduced ATP hydrolysis26 C65 Deleterious Benign Disease causing c.3322C>T p.R1108C Reduced ATP binding26 C65 Deleterious Probably damaging Disease causing c.4102C>T p.R1368C C65 Deleterious Probably damaging Disease causing c.4462T>C p.C1488R C65 Deleterious Possibly damaging Disease causing c.4469G>A p.C1490Y Misfolding, mislocali- zation27 C65 Deleterious Probably damaging Disease causing Cryptic donor strongly activated c.4926C>G p.S1642R C25 Deleterious Benign Disease causing c.6079C>T p.L2027F Reduced ATP binding26,29 C15 Deleterious Probably damaging Disease causing c.6089G>A p.R2030Q C35 Deleterious Probably damaging Disease causing c.6229C>T p.R2077W Reduced ATP binding26 C65 Deleterious Probably damaging Disease causing Deletion/frame-shift/stop variants c.666_678del p.K223_ R226delfs c.2041C>T p.R681* c.2408delG p.G803fs c.4234C>T p.Q1412* c.5041_5055del p.V1681_ C1685del c.5169C>G p.Y1723* Splicing affecting variants c.3191-2A>G Predicted change at acceptor site 2 bps downstream: 100% c.3329-2A>G Predicted change at acceptor site 2 bps downstream: 100% c.4667&#fe;2T>C Predicted change at donor site 2 bps upstream: 100% generalized choriocapillaris dystrophy have the occasional hallmarks of early Stargardt disease, such as vermillion fundus, fundus hyperautofluorescence, and a dark choroid on fluorescein angiograms. Login to comment

[hide] The external limiting membrane in early-onset Star... Invest Ophthalmol Vis Sci. 2014 Aug 19;55(10):6139-49. doi: 10.1167/iovs.14-15126. Lee W, Noupuu K, Oll M, Duncker T, Burke T, Zernant J, Bearelly S, Tsang SH, Sparrow JR, Allikmets R
The external limiting membrane in early-onset Stargardt disease.
Invest Ophthalmol Vis Sci. 2014 Aug 19;55(10):6139-49. doi: 10.1167/iovs.14-15126., [PMID:25139735]

Abstract [show]
PURPOSE: To describe pathologic changes of the external limiting membrane (ELM) in young patients with early-onset Stargardt (STGD1) disease. METHODS: Twenty-six STGD1 patients aged younger than 20 years with confirmed disease-causing adenosine triphosphate-binding cassette, subfamily A, member 4 (ABCA4) alleles and 30 age-matched unaffected individuals were studied. Spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence (AF), and color fundus photography (CFP) images, as well as full-field electroretinograms were obtained and analyzed for one to four visits in each patient. RESULTS: The ELM in all patients exhibited a distinct thickening that was not observed in unaffected individuals. In addition, accumulations of reflective deposits were noted in the outer nuclear layer in every patient. Four patients exhibited a concave protuberance or bulging of a thickened and hyperreflective ELM band within the fovea containing preserved photoreceptors. Longitudinal SD-OCT data in several patients revealed the persistence of this ELM abnormality over a period of time (1-4 years). Furthermore, the edges of the inner segment ellipsoid band appeared to recede earlier than the ELM band in active lesions. CONCLUSIONS: Structural changes seen in the ELM of this cohort may reflect a gliotic response to cellular stress at the photoreceptor level in early-onset STGD1.

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89 [L541P;A1038V] p.L2027F P8 10 Caucasian 20/40 (0.30) 20/80 (0.60) 1 1 None-early 1 p.R1108C p.Q1412* P9 14 Caucasian 20/100 (0.70) 20/100 (0.70) 2 1 Early-late 0.5 p.T972N p.L2027F P10 9 Caucasian 20/150 (0.88) 20/400 (1.30) 2 1 Late ND c.5312&#fe;1G>A p.R2030* P11 15 Caucasian 20/200 (1.00) 20/200 (1.00) 2 2 Mid-late 3 p.L2027F p.R2077W P12 5 Caucasian 20/30 (0.18) 20/40 (0.30) 1 n/a ND c.5018&#fe;2T>C p.G1961E P13 10 Caucasian 20/200 (1.00) 20/200 (1.00) 2 2 Mid 4 p. 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] Correlations among near-infrared and short-wavelen... Invest Ophthalmol Vis Sci. 2014 Oct 23;55(12):8134-43. doi: 10.1167/iovs.14-14848. Duncker T, Marsiglia M, Lee W, Zernant J, Tsang SH, Allikmets R, Greenstein VC, Sparrow JR
Correlations among near-infrared and short-wavelength autofluorescence and spectral-domain optical coherence tomography in recessive Stargardt disease.
Invest Ophthalmol Vis Sci. 2014 Oct 23;55(12):8134-43. doi: 10.1167/iovs.14-14848., [PMID:25342616]

Abstract [show]
PURPOSE: Short-wavelength (SW) fundus autofluorescence (AF) is considered to originate from lipofuscin in retinal pigment epithelium (RPE) and near-infrared (NIR) AF from melanin. In patients with recessive Stargardt disease (STGD1), we correlated SW-AF and NIR-AF with structural information obtained by spectral-domain optical coherence tomography (SD-OCT). METHODS: Twenty-four STGD1 patients (45 eyes; age 8 to 61 years) carrying confirmed disease-associated ABCA4 mutations were studied prospectively. Short-wavelength AF, NIR-AF, and SD-OCT images were acquired. RESULTS: Five phenotypes were identified according to features of the central lesion and extent of fundus change. Central zones of reduced NIR-AF were typically larger than areas of diminished SW-AF and reduced NIR-AF usually approximated areas of ellipsoid zone (EZ) loss identified by SD-OCT (group 1; r, 0.93, P < 0.0001). In patients having a central lesion with overlapping parafoveal rings of increased NIR-AF and SW-AF (group 3), the extent of EZ loss was strongly correlated with the inner diameter of the NIR-AF ring (r, 0.89, P < 0.0001) and the eccentricity of the outer border of the NIR-AF ring was greater than that of the SW-AF ring. CONCLUSIONS: Lesion areas were more completely delineated in NIR-AF images than with SW-AF. In most cases, EZ loss was observed only at locations where NIR-AF was reduced or absent, indicating that RPE cell atrophy occurs in advance of photoreceptor cell degeneration. Because SW-AF was often increased within the central area of EZ disruption, degenerating photoreceptor cells may produce lipofuscin at accelerated levels. Consideration is given to mechanisms underlying hyper-NIR-AF in conjunction with increased SW-AF.

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91 [L541P;A1038V] 5 14 22.4 F White Brown 0.8 0.8 p.R212C 3 15 20.2 M White Brown 0.9 0.9 p.G1961E p.P1380L 1 16 27.6 M Arabic Brown 0.0 0.0 p.R1300* p.R2106C 3 17 26.8 M White Blue 0.5 0.5 p.G1961E c.3050&#fe;5G>A 1 18 24.9 F White Hazel 0.9 0.9 p.G1961E p.C2150R 5 19 13.2 M White Blue 0.9 1.0 p.W821R p.C2150Y 3 20 61.0 F White Green 2.0 0.0 c.250_251insCAAA 2 21 36.3 F White Blue 1.3 0.1 p.N1799D 1 22 14.1 F White Green 1.0 0.9 p.R1108C p.Q1412* 2 23 18.6 M White Brown 0.9 0.9 p.G1961E p.A1773V 3 24 53.3 F White Blue 0.3 (0.2) p.R2077W 2 BCVA values in parenthesis indicate fellow eyes that were not included in the study. 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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62 Continued Subject Sex Age Race/ Ethnicity Relationship to Proband ABCA4 Mutation BCVA, logMAR Eye Segmented qAF8 OD OS OD OS S38.3 M 50.9 White Father p.C2150Y 0.00 0.00 OS 336 380 S39.3 F 42.5 White Mother c.5714&#fe;5G>A 0.00 0.00 n/a 462 393 S39.4 F 18.4 White Sister c.5714&#fe;5G>A 0.00 0.00 n/a 222 212 S40.2 F 50.1 White Mother p.R2030Q 0.00 0.00 OD 433 n/a S40.3 M 48.8 White Father p.K1547* 0.00 0.00 OS n/a 477 S41.2 F 60.3 White Mother p.C54Y 0.00 0.00 OS n/a n/a S42.2 F 44.5 White Mother p.Q1412* 0.10 0.00 OS 264 291 S42.3 M 44.2 White Father p.R1108C 0.30 0.18 OD 264 232 S43.2 F 44.9 White Mother p.G1961E 0.00 0.00 OS 404 n/a S44.3 M 37.1 Asian Father c.4248_4250del 0.00 0.00 OD 307 317 S45.2 F 66.3 White Mother p.N965Y 0.18 0.40 n/a n/a n/a S45.3 M 68.0 White Father p.P1486L 0.00 0.00 n/a n/a n/a S46 M 32.3 White Spouseߤ p.T897I 0.12 0.12 OD 194 200 BCVA, best-corrected visual acuity; logMAR, logarithm of the minimum angle of resolution; OD, right eye; OS, left eye; qAF8, average quantitative autofluorescence of the 8 measurement sites from all available images per eye; n/a, not available. Login to comment
75 [W1408R;R1640W] 1.00 1.00 n/a n/a P 33.1&#a7; M 23.0 White p.R2030Q p.G1961E 1.00 1.00 334 347 P 34.1 M 46.9 White p.C1490Y p.G1961E 0.40 0.30 376 384 P 35.1ߥ M 24.8 White c.3050&#fe;5G>A p.G1961E 0.00 0.00 381 451 P 36.1ߥ F 29.3 Hispanic p.L541P p.G1961E 0.40 0.40 479 487 P 37.1ߤ F 24.7 White p.G1961E p.C2150R 0.88 0.88 405 396 P 38.1&#a7; M 11.7 White p.W821R p.C2150Y 0.40 0.40 306 n/a P 39.1 F 12.8 White p.P1380L c.5714&#fe;5G>A 0.60 0.40 558 573 P 39.2 M 14.1 White p.P1380L c.5714&#fe;5G>A 0.88 0.88 395 462 P 40.1ߤ F 16.2 White p.K1547* p.R2030Q 0.70 0.40 481 513 P 41.1 F 19.0 White p.C54Y 0.88 0.88 n/a n/a P 42.1ߤ F 13.0 White p.R1108C p.Q1412* 1.30 1.00 511 528 P 43.1ߤ M 17.4 White p.A1773V p.G1961E 0.88 0.88 340 366 P 44.1 M 14.0 Asian p.R408* c.4248_4250del 1.30 1.30 n/a n/a P 44.2 F 7.0 Asian p.R408* c.4248_4250del 1.30 1.30 n/a n/a P 45.1 F 42.4 White p.N965Y p.P1486L 0.10 0.40 n/a n/a BCVA, best-corrected visual acuity; logMAR, logarithm of the minimum angle of resolution; OD, right eye; OS, left eye; qAF8, average quantitative autofluorescence of the 8 measurement sites from all available images per eye; n/a, not available. 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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102 The third most frequent ABCA4 mutation is p.Q1412*, which was identified in 10 patients (Table 2, Supplementary Tables S1 and S2). Login to comment