ABCMdb

ABCA4 p.Thr1253Met

ClinVar:	c.3759G>A , p.Thr1253= N , Benign c.3758C>T , p.Thr1253Met ? , not provided
Predicted by SNAP2:	A: N (78%), C: N (72%), D: N (72%), E: N (78%), F: N (57%), G: N (72%), H: N (87%), I: N (72%), K: N (82%), L: N (66%), M: N (72%), N: N (87%), P: N (66%), Q: N (78%), R: N (78%), S: N (93%), V: N (78%), W: D (66%), Y: N (61%),
Predicted by PROVEAN:	A: N, C: D, D: N, E: N, F: D, G: D, H: N, I: D, K: N, L: D, M: N, N: N, P: D, Q: N, R: N, S: N, V: D, W: D, Y: D,

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[hide] Retinal phenotypes in patients homozygous for the ... Invest Ophthalmol Vis Sci. 2012 Jul 3;53(8):4458-67. doi: 10.1167/iovs.11-9166. Print 2012 Jul. Burke TR, Fishman GA, Zernant J, Schubert C, Tsang SH, Smith RT, Ayyagari R, Koenekoop RK, Umfress A, Ciccarelli ML, Baldi A, Iannaccone A, Cremers FP, Klaver CC, Allikmets R
Retinal phenotypes in patients homozygous for the G1961E mutation in the ABCA4 gene.
Invest Ophthalmol Vis Sci. 2012 Jul 3;53(8):4458-67. doi: 10.1167/iovs.11-9166. Print 2012 Jul., [PMID:22661473]

Abstract [show]
PURPOSE: We evaluated the pathogenicity of the G1961E mutation in the ABCA4 gene, and present the range of retinal phenotypes associated with this mutation in homozygosity in a patient cohort with ABCA4-associated phenotypes. METHODS: Patients were enrolled from the ABCA4 disease database at Columbia University or by inquiry from collaborating physicians. Only patients homozygous for the G1961E mutation were enrolled. The entire ABCA4 gene open reading frame, including all exons and flanking intronic sequences, was sequenced in all patients. Phenotype data were obtained from clinical history and examination, fundus photography, infrared imaging, fundus autofluorescence, fluorescein angiography, and spectral domain-optical coherence tomography. Additional functional data were obtained using the full-field electroretinogram, and static or kinetic perimetry. RESULTS: We evaluated 12 patients homozygous for the G1961E mutation. All patients had evidence of retinal pathology consistent with the range of phenotypes observed in ABCA4 disease. The latest age of onset was recorded at 64 years, in a patient diagnosed initially with age-related macular degeneration (AMD). Of 6 patients in whom severe structural (with/without functional) fundus changes were detected, 5 had additional, heterozygous or homozygous, variants detected in the ABCA4 gene. CONCLUSIONS: Homozygous G1961E mutation in ABCA4 results in a range of retinal pathology. The phenotype usually is at the milder end of the disease spectrum, with severe phenotypes linked to the presence of additional ABCA4 variants. Our report also highlights that milder, late-onset Stargardt disease may be confused with AMD.

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89 Patient 3 had an additional heterozygous T1253M variant. Login to comment
91 Summary of Demographic, Clinical, and Functional Data in Patients Homozygous for the G1961E Mutation Patient #, Sex Additional ABCA4 Mutations Onset Age (years) Age at Exam (years) Duration (years) VA Clinical Phenotype ERG Group Silent Choroid Type of Perimetry Scotoma Location OD OS Milder Phenotypes 1, M 19 34 15 20/150 20/100 I I ND MP-1 Central 2, F 20 21 1 20/25 20/40 I I Absent ND ND 3, M T1253M 32 46 14 20/25 20/40 I I Absent GVF Perifoveal 4, F 43 67 24 20/40 20/150 II I ND MP-1 Central 5, F 48 65 17 20/150 20/200 I I ND MP-1 Central 6, F 64 86 22 20/200 20/200 II I Absent GVF Central Severe Phenotypes 7-1, M H1838D (Hom) 4 12 8 20/250 20/250 III III ND GVF Central 7-2, F H1838D (Hom) 7 13 6 20/200 20/200 IV III Peripapillary Ring GVF Central 8-1, F N96K 7 46 39 20/2000 20/2000 III III Peripapillary Ring GVF Central 8-2, M N96K 10 49 39 20/400 20/400 IV ND ND GVF Central 9, F N96K (Hom) 12 59 47 10/400 10/400 IV III ND ND ND 10, M 20 51 31 20/25 20/25 III RP ND GVF Perifoveal Each number identifies distinct families. Login to comment
106 Only one patient in this group (patient 3) had a heterozygous T1253M variant detected in the ABCA4 gene, in addition to the homozygous G1961E mutation. Login to comment
167 Six patients had other ABCA4 variants on the same chromosome with G1961E. Login to comment
168 One patient harbored a heterozygous T1253M variant, which previously has been reported sometimes to form a complex allele with G1961E.41 It is predicted to give rise to an amino acid change that lies outside the functional domain of the ABCA4 protein, it never occurs without G1961E, and, therefore, its pathogenicity has not been confirmed. Login to comment
88 Patient 3 had an additional heterozygous T1253M variant. Login to comment
90 Summary of Demographic, Clinical, and Functional Data in Patients Homozygous for the G1961E Mutation Patient #, Sex Additional ABCA4 Mutations Onset Age (years) Age at Exam (years) Duration (years) VA Clinical Phenotype ERG Group Silent Choroid Type of Perimetry Scotoma Location OD OS Milder Phenotypes 1, M 19 34 15 20/150 20/100 I I ND MP-1 Central 2, F 20 21 1 20/25 20/40 I I Absent ND ND 3, M T1253M 32 46 14 20/25 20/40 I I Absent GVF Perifoveal 4, F 43 67 24 20/40 20/150 II I ND MP-1 Central 5, F 48 65 17 20/150 20/200 I I ND MP-1 Central 6, F 64 86 22 20/200 20/200 II I Absent GVF Central Severe Phenotypes 7-1, M H1838D (Hom) 4 12 8 20/250 20/250 III III ND GVF Central 7-2, F H1838D (Hom) 7 13 6 20/200 20/200 IV III Peripapillary Ring GVF Central 8-1, F N96K 7 46 39 20/2000 20/2000 III III Peripapillary Ring GVF Central 8-2, M N96K 10 49 39 20/400 20/400 IV ND ND GVF Central 9, F N96K (Hom) 12 59 47 10/400 10/400 IV III ND ND ND 10, M 20 51 31 20/25 20/25 III RP ND GVF Perifoveal Each number identifies distinct families. Login to comment
105 Only one patient in this group (patient 3) had a heterozygous T1253M variant detected in the ABCA4 gene, in addition to the homozygous G1961E mutation. Login to comment

[hide] Transition zones between healthy and diseased reti... Invest Ophthalmol Vis Sci. 2011 Dec 20;52(13):9581-90. Print 2011. Lazow MA, Hood DC, Ramachandran R, Burke TR, Wang YZ, Greenstein VC, Birch DG
Transition zones between healthy and diseased retina in choroideremia (CHM) and Stargardt disease (STGD) as compared to retinitis pigmentosa (RP).
Invest Ophthalmol Vis Sci. 2011 Dec 20;52(13):9581-90. Print 2011., [PMID:22076985]

Abstract [show]
PURPOSE: To describe the structural changes across the transition zone (TZ) in choroideremia (CHM) and Stargardt disease (STGD) and to compare these to the TZ in retinitis pigmentosa (RP). METHODS: Frequency-domain (Fd)OCT line scans were obtained from seven patients with CHM, 20 with STGD, and 12 with RP and compared with those of 30 previously studied controls. A computer-aided manual segmentation procedure was used to determine the thicknesses of the outer segment (OS) layer, the outer nuclear layer plus outer plexiform layer (ONL+), the retinal pigment epithelium plus Bruch's membrane (RPE+BM), and the outer retina (OR). RESULTS: The TZ, while consistent within patient groups, showed differences across disease groups. In particular, (1) OS loss occurred before ONL+ loss in CHM and RP, whereas ONL+ loss occurred before OS loss in STGD; (2) ONL+ was preserved over a wider region of the retina in CHM than in RP; (3) RPE+BM remained normal across the RP TZ, but was typically thinned in CHM. In some CHM patients, it was abnormally thin in regions with normal OS and ONL+ thickness. In STGD, RPE+BM was thinned by the end of the TZ; and (4) the disappearances of the IS/OS and OLM were more abrupt in CHM and STGD than in RP. CONCLUSIONS: On fdOCT scans, patients with RP, CHM, and STGD all have a TZ between relatively healthy and severely affected retina. The patterns of changes in the receptor layers are similar within a disease category, but different across categories. The findings suggest that the pattern of progression of each disease is distinct and may offer clues for strategies in the development of future therapies.

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59 Characteristics of Patients with STGD Patient ID Eye Age Sex BCVA Mutation(s) (ABCA4) P8 12 OS 33 F 20/150 G1961E P9 2 OS 30 M 20/150 T1253M, G1961E P10 9817 OS 21 F 20/63 * P11 9 OS 19 M 20/150 IVS20ϩ5 GϾA, G1961E P12 6953 OD 49 F 20/50 * P13 11 OS 59 M 20/100 P1380L, S1696N P14 9831 OD 28 M 20/500 * P15 8813 OD 13 M 20/50 * P16 8 OS 34 M 20/100 G1961E, G1961E P17 6.1 OD 24 F 20/200 L541P/A1038V, G1961E P18 8833 OS 13 F 20/160 N965S, L2229P P19 8938 OD 13 M 20/200 A192T, R1300Q P20 5470 OD 28 F 20/100 * P21 9901 OS 41 M 20/160 I32V P22 9327 OS 11 F 20/63 G863A, A1695D P23 9386 OS 18 M 20/40 * P24 8862 OD 30 F 20/63 * P25 6.1 OD 21 F 20/150 L541P/A1038V, G1961E P26 6.2 OS 18 F 20/70 L541P/A1038V, G1961E P27 10 OS 23 F 20/150 L541P/A1038V, I1846T * Patient did not undergo genetic testing. Login to comment
31 Characteristics of Patients with STGD Patient ID Eye Age Sex BCVA Mutation(s) (ABCA4) P8 12 OS 33 F 20/150 G1961E P9 2 OS 30 M 20/150 T1253M, G1961E P10 9817 OS 21 F 20/63 * P11 9 OS 19 M 20/150 IVS20af9;5 Gb0e;A, G1961E P12 6953 OD 49 F 20/50 * P13 11 OS 59 M 20/100 P1380L, S1696N P14 9831 OD 28 M 20/500 * P15 8813 OD 13 M 20/50 * P16 8 OS 34 M 20/100 G1961E, G1961E P17 6.1 OD 24 F 20/200 L541P/A1038V, G1961E P18 8833 OS 13 F 20/160 N965S, L2229P P19 8938 OD 13 M 20/200 A192T, R1300Q P20 5470 OD 28 F 20/100 * P21 9901 OS 41 M 20/160 I32V P22 9327 OS 11 F 20/63 G863A, A1695D P23 9386 OS 18 M 20/40 * P24 8862 OD 30 F 20/63 * P25 6.1 OD 21 F 20/150 L541P/A1038V, G1961E P26 6.2 OS 18 F 20/70 L541P/A1038V, G1961E P27 10 OS 23 F 20/150 L541P/A1038V, I1846T * Patient did not undergo genetic testing. Login to comment

[hide] Quantification of peripapillary sparing and macula... Invest Ophthalmol Vis Sci. 2011 Oct 10;52(11):8006-15. Print 2011. Burke TR, Rhee DW, Smith RT, Tsang SH, Allikmets R, Chang S, Lazow MA, Hood DC, Greenstein VC
Quantification of peripapillary sparing and macular involvement in Stargardt disease (STGD1).
Invest Ophthalmol Vis Sci. 2011 Oct 10;52(11):8006-15. Print 2011., [PMID:21873672]

Abstract [show]
PURPOSE: To quantify and compare structure and function across the macula and peripapillary area in Stargardt disease (STGD1). METHODS: Twenty-seven patients (27 eyes) and 12 age-similar controls (12 eyes) were studied. Patients were classified on the basis of full-field electroretinogram (ERG) results: Fundus autofluorescence (FAF) and spectral domain-optical coherence tomography (SD-OCT) horizontal line scans were obtained through the fovea and peripapillary area. The thicknesses of the outer nuclear layer plus outer plexiform layer (ONL+), outer segment (OS), and retinal pigment epithelium (RPE) were measured through the fovea, and peripapillary areas from 1 degrees to 4 degrees temporal to the optic disc edge using a computer-aided, manual segmentation technique. Visual sensitivities in the central 10 degrees were assessed using microperimetry and related to retinal layer thicknesses. RESULTS: Compared to the central macula, the differences between controls and patients in ONL+, OS, and RPE layer thicknesses were less in the nasal and temporal macula. Relative sparing of the ONL+ and/or OS layers was detected in the nasal (i.e., peripapillary) macula in 8 of 13 patients with extramacular disease on FAF; relative functional sparing was also detected in this subgroup. All 14 patients with disease confined to the central macula, as detected on FAF, showed ONL+ and OS layer thinning in regions of normal RPE thickness. CONCLUSIONS: Relative peripapillary sparing was detected in STGD1 patients with extramacular disease on FAF. Photoreceptor thinning may precede RPE degeneration in STGD1.

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112 Summary of Clinical, Demographic, and Genetic Data Patient Sex Age at Exam (y) Eye VA BCEA 1 SD (deg 2 ) Eccentricity of PRL (deg) ERG Group FAF Abnormalities Allele 1 Allele 2 Allele 3 Distribution Peripapillary Area 1 F 43 OS 20/20 0.73 0 II M - A1799D ND ND 2 M 30 OS 20/150 3.21 6 I M - T1253M G1961E ND 3 F 55 OD 20/30 1.82 0 I EM - G863A IVS28af9;5 Gb0e;T ND 4 M 44 OD 20/25 0.65 0 I M - E161K ND ND 5.1 F 24 OD 20/200 1.57 1 I M - L541P/A1038V G1961E ND 5.2 F 22 OD 20/30 2.74 1 I M - L541P/A1038V G1961E ND 6.1 F 21 OD 20/150 2.01 1 I M - L541P/A1038V G1961E ND 6.2 F 18 OS 20/100 3.09 4 I M - L541P/A1038V G1961E ND 7 F 27 OS 20/400 2.97 9* II EM Peripapillary atrophy L2027F G851D ND 8 M 34 OS 20/100 2.16 4 I M - G1961E G1961E ND 9 M 20 OS 20/150 2.77 4 I M - IVS20af9;5 Gb0e;A G1961E ND 10 F 23 OS 20/150 9.05 5 I M - L541P/A1038V I1846T ND 11 M 59 OS 20/100 6.52 10 II EM - P1380L S1696N ND 12 M 49 OD 20/150 9.97 1 I EM Nasalaf9;temporal flecks R1108H P1380L ND 13 M 47 OS 20/80 5.62 7 I EM - G863A Y106X ND 14 F 42 OD 20/200 9.53 9 I EM Temporal flecks N965S ND ND 15 M 14 OD 20/200 23.84 1 II EM Nasal flecks IVS38-10 Tb0e;C IVS40af9;5 Gb0e;A ND 16 M 52 OS 20/20 1.3 0 I M - IVS38-10 Tb0e;C ND ND 17 M 34 OS 20/30 2.8 1 I M - L541P/A1038V G1961E ND 18 F 33 OD 20/100 6 6 I M - G1961E R2077W ND 19 F 22 OS 20/60 11 4 I M - A854T A1038V C2150Y 20 F 34 OS 20/200 14.2 14 I EM - G1961E ND ND 21 F 19 OD 20/200 3.7 12 I EM - R602W M18821 ND 22 F 27 OD 20/400 9.6 9 II EM Peripapillary atrophy P1380L P1380L ND 23 F 18 OS 20/50 4.9 5 I EM - R1640W V1693I ND 24 M 22 OS 20/150 10.5 2 I EM - C54Y ND ND 25 M 44 OS 20/150 9.1 5 I EM - R1640W ND ND VA, visual acuity; Rel. Login to comment

[hide] G1961E mutant allele in the Stargardt disease gene... Exp Eye Res. 2009 Jun 15;89(1):16-24. Epub 2009 Feb 13. Cella W, Greenstein VC, Zernant-Rajang J, Smith TR, Barile G, Allikmets R, Tsang SH
G1961E mutant allele in the Stargardt disease gene ABCA4 causes bull's eye maculopathy.
Exp Eye Res. 2009 Jun 15;89(1):16-24. Epub 2009 Feb 13., [PMID:19217903]

Abstract [show]
The aim of this study was to characterize the pathological and functional consequences of the G1961E mutant allele in the Stargardt disease gene ABCA4. Data from 15 patients were retrospectively reviewed and all the patients had at least one G1961E mutation. Comprehensive ophthalmic examination, full-field and pattern electroretinograms, and fundus autofluorescence (FAF) imaging were performed on all patients. Microperimetry, spectral-domain optical coherence tomography (OCT), and fluorescein angiography were performed in selected cases. Genetic screening was performed using the ABCR400 micro-array that currently detects 496 distinct ABCA4 variants. All patients had normal full-field scotopic and photopic electroretinograms (ERGs) and abnormal pattern electroretinograms (PERGs) performed on both eyes, and all the fundi had bull's eye maculopathy without retinal flecks on FAF. On OCT, 1 patient had disorganization of photoreceptor outer segment, 2 had outer nuclear layer (ONL) thinning likely due to photoreceptor atrophy proximal to the foveal center, and 3 had additional retinal pigment epithelium (RPE) atrophy. On microperimetry, 6 patients had eccentric superior fixation and amongst this group, 5 had an absolute scotoma in the foveal area. DNA analysis revealed that 3 patients were homozygous G1961E/G1961E and the rest were compound heterozygotes for G1961E and other ABCA4 mutations. The G1961E allele in either homozygosity or heterozygosity is associated with anatomical and functional pathologies limited to the parafoveal region and a trend to delayed onset of symptoms, relative to other manifestations of ABCA4 mutations. Our observations support the hypothesis that the G1961E allele contributes to localized macular changes rather than generalized retinal dysfunction, and is a cause of bull's eye maculopathy in either the homozygosity or heterozygosity state. In addition, genetic testing provides precise diagnosis of the underlying maculopathy, and current non-invasive imaging techniques could be used to detect photoreceptor damage at the earliest clinical onset of the disease.

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89 Of the compound heterozygous group, 5 patients from 2 families had the complex mutation L541P/A1038V, 2 patients (siblings) had the splicing mutation IVS20 þ 5G / A, and 5 patients had missense mutations Q636H, R2077W, T1253M, C54Y and D1532N (Table 1). Login to comment
131 In 5 patients (patients 7-11), missense mutations Q636H, R2077W, T1253M, C54Y and D1532N were found in addition to the G1961E allele, respectively. Login to comment
142 Case #, sex Age of onset Duration (years) Visual acuity (OD, OS) Allele 2 Bull`s eye type (FAF) SD-OCT MP-1 1, f 20 1 20/25, 20/40 G1961E (homozygous) B Not tested Not tested 2, f 49 13 20/200, 20/150 G1961E (homozygous) B Photoreceptor loss, thinner ONL and RPE atrophy Absolute scotoma in the central 4 degrees OD and in the central 6 degrees OS, eccentric PRL (superior retina) 3, m 19 13 20/70, 20/70 G1961E (homozygous) A Not tested Absolute scotoma in the central 6 degrees in both eyes, eccentric PRL (superior retina) 4.1, f 17 30 20/200, 20/200 L541P/A1038V B Not tested Not tested 4.2, m 28 2 20/25, 20/30 L541P/A1038V B Not tested Decreased sensitivity by 6 dB in the central 2 degrees in both eyes, foveal fixation 4.3, m 28 2 20/30, 20/40 L541P/A1038V B Not tested Decreased sensitivity by 9 dB OD and 11 dB OS in the central 2 degrees, foveal fixation 5.1, f 14 5 20/200, 20/400 L541P/A1038V C Photoreceptor loss (foveal optical gap), thinner ONL and normal RPE Decreased sensitivity by 8 dB in the central 2 degrees in both eyes, eccentric PRL (superior retina) 5.2, f 14 1 20/20, 20/25 L541P/A1038V A Photoreceptor disorganization, normal ONL and normal RPE Decreased sensitivity by 6 dB in the central 2 degrees in both eyes, foveal fixation 6.1, f 17 5 20/100, 20/100 IVS20 þ 5G / A C Photoreceptor loss, thinner ONL and RPE atrophy Absolute scotoma in the central 2 degrees in both eyes, eccentric PRL (superior retina) 6.2, m 14 3 20/40, 20/25 IVS20 þ 5G / A A Photoreceptor loss (foveal optical gap), thinner ONL and normal RPE Absolute scotoma in the central 2 degrees OD and decreased sensitivity by 18 dB in the central 2 degrees OS, eccentric PRL (superior retina) 7, m 28 12 20/200, 20/150 Q636H B Photoreceptor loss, thinner ONL and RPE atrophy Not tested 8, f 25 9 20/80, 20/25 R2077W B Not tested Not tested 9, m 67 2 20/800, 20/60 T1253M B Not tested Not tested 10, f 26 10 20/80, 20/80 C54Y B Not tested Not tested 11, f 44 20 20/400, 20/60 D1532N C Not tested Absolute scotoma in the central 8-10 degrees OD and absolute scotoma in the central 8 degrees OS, eccentric PRL (superior retina) Abbreviations: m, male; f, female; OD, right eye; OS, left eye; FAF, fundus autofluorescence; bull`s eye type A, presence of a ring of increase autofluorescence surrounding decreased autofluorescence; bull`s eye type B, decreased fovea autofluorescence without a surrounding ring of increase autofluorescence; bull`s eye type C, speckled macular appearance with slightly increased surround autofluorescence; SD-OCT, spectral-domain optical coherence tomography; ONL, outer nuclear layer; MP-1, microperimetry; and PRL, preferred retinal location. Login to comment
182 An exception was patient 9 with the missense mutation T1253M that imparts an amino acid change outside of ABCA4 functional domain and presented with poor visual acuity but uncertain disease duration. Login to comment
184 Finally, patient 8 had the missense mutation R2077W in addition to the G1961E allele and a mild-to-moderate phenotype, with asymmetrical visual acuity and discrete autofluorescence changes. Login to comment
143 Case #, sex Age of onset Duration (years) Visual acuity (OD, OS) Allele 2 Bull`s eye type (FAF) SD-OCT MP-1 1, f 20 1 20/25, 20/40 G1961E (homozygous) B Not tested Not tested 2, f 49 13 20/200, 20/150 G1961E (homozygous) B Photoreceptor loss, thinner ONL and RPE atrophy Absolute scotoma in the central 4 degrees OD and in the central 6 degrees OS, eccentric PRL (superior retina) 3, m 19 13 20/70, 20/70 G1961E (homozygous) A Not tested Absolute scotoma in the central 6 degrees in both eyes, eccentric PRL (superior retina) 4.1, f 17 30 20/200, 20/200 L541P/A1038V B Not tested Not tested 4.2, m 28 2 20/25, 20/30 L541P/A1038V B Not tested Decreased sensitivity by 6 dB in the central 2 degrees in both eyes, foveal fixation 4.3, m 28 2 20/30, 20/40 L541P/A1038V B Not tested Decreased sensitivity by 9 dB OD and 11 dB OS in the central 2 degrees, foveal fixation 5.1, f 14 5 20/200, 20/400 L541P/A1038V C Photoreceptor loss (foveal optical gap), thinner ONL and normal RPE Decreased sensitivity by 8 dB in the central 2 degrees in both eyes, eccentric PRL (superior retina) 5.2, f 14 1 20/20, 20/25 L541P/A1038V A Photoreceptor disorganization, normal ONL and normal RPE Decreased sensitivity by 6 dB in the central 2 degrees in both eyes, foveal fixation 6.1, f 17 5 20/100, 20/100 IVS20 &#fe; 5G / A C Photoreceptor loss, thinner ONL and RPE atrophy Absolute scotoma in the central 2 degrees in both eyes, eccentric PRL (superior retina) 6.2, m 14 3 20/40, 20/25 IVS20 &#fe; 5G / A A Photoreceptor loss (foveal optical gap), thinner ONL and normal RPE Absolute scotoma in the central 2 degrees OD and decreased sensitivity by 18 dB in the central 2 degrees OS, eccentric PRL (superior retina) 7, m 28 12 20/200, 20/150 Q636H B Photoreceptor loss, thinner ONL and RPE atrophy Not tested 8, f 25 9 20/80, 20/25 R2077W B Not tested Not tested 9, m 67 2 20/800, 20/60 T1253M B Not tested Not tested 10, f 26 10 20/80, 20/80 C54Y B Not tested Not tested 11, f 44 20 20/400, 20/60 D1532N C Not tested Absolute scotoma in the central 8-10 degrees OD and absolute scotoma in the central 8 degrees OS, eccentric PRL (superior retina) Abbreviations: m, male; f, female; OD, right eye; OS, left eye; FAF, fundus autofluorescence; bull`s eye type A, presence of a ring of increase autofluorescence surrounding decreased autofluorescence; bull`s eye type B, decreased fovea autofluorescence without a surrounding ring of increase autofluorescence; bull`s eye type C, speckled macular appearance with slightly increased surround autofluorescence; SD-OCT, spectral-domain optical coherence tomography; ONL, outer nuclear layer; MP-1, microperimetry; and PRL, preferred retinal location. 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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43 Of note, AR468-8 was heterozygous for three mutations: the transitions 3758C→T (encoding the missense mutation T1253M), 4139C→T (encoding the missense mutation P1380L) and 5882G→A (encoding the missense mutation G1961E). Login to comment
44 Segregation analysis in this family revealed that two alterations (T1253M and G1961E) were on the same chromosome; thus AR468-8 is compound heterozygous for a novel complex allele [T1253M; G1961E] and the missense mutation P1380L (Fig. 1). Login to comment
47 Two novel mutations were identified in this cohort: the missense mutation T1253M was identified as part of the complex allele [T1253M; G1961E] and the transition 1648G→A (encoding the missense mutation G550R) was identified in STGD-affected AR484-4. 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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99 The third ABCA4 complex allele contained the previously reported p.T1253M present in cis with p.G1961E (Paloma et al., 2001). Login to comment
101 [(T1253M; G1961E)] complex allele, the p.G1961E mutation was identified in 21 other unrelated probands, which makes it the second most frequent disease-causing ABCA4 change in our patients. Login to comment
151 [(T1253M; G1961E)] (1/184) x x ZGM: exome data for the Polish population; The number of mutant and total alleles detected is given in brackets; x e no ABCA4 diseases-associated variant detected. Login to comment