ABCMdb

ABCA4 p.His1838Asp

ClinVar:	c.5512C>T , p.His1838Tyr ? , not provided c.5512C>G , p.His1838Asp ? , not provided
Predicted by SNAP2:	A: D (75%), C: D (75%), D: D (91%), E: D (66%), F: D (71%), G: D (75%), I: D (71%), K: D (63%), L: D (71%), M: D (66%), N: D (66%), P: D (80%), Q: D (63%), R: D (59%), S: D (66%), T: D (63%), V: D (66%), W: D (85%), Y: D (91%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: 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] 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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87 Two other siblings (patients 7-1 and 7-2), who belonged to a consanguineous Jordanian family, also had the H1838D mutation detected in homozygosity, in addition to being homozygous for the G1961E mutation. 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
184 These genetic findings in our patients of Italian origin are in keeping with recent reports of this mutation in Italian populations with STGD1.43 The H1838D mutation has been reported previously in patient 7-1.31 This variant clearly has a profoundly deleterious effect on ABCA4 protein function, at least when present in conjunction with the G1961E in homozygosity, giving rise to a severe, early-onset and complex phenotype in both siblings from a consanguineous family of Jordanian descent. Login to comment
86 Two other siblings (patients 7-1 and 7-2), who belonged to a consanguineous Jordanian family, also had the H1838D mutation detected in homozygosity, in addition to being homozygous for the G1961E mutation. 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
183 These genetic findings in our patients of Italian origin are in keeping with recent reports of this mutation in Italian populations with STGD1.43 The H1838D mutation has been reported previously in patient 7-1.31 This variant clearly has a profoundly deleterious effect on ABCA4 protein function, at least when present in conjunction with the G1961E in homozygosity, giving rise to a severe, early-onset and complex phenotype in both siblings from a consanguineous family of Jordanian descent. Login to comment

[hide] Outcome of ABCA4 disease-associated alleles in aut... Ophthalmology. 2013 Nov;120(11):2332-7. doi: 10.1016/j.ophtha.2013.04.002. Epub 2013 Jun 4. Riveiro-Alvarez R, Lopez-Martinez MA, Zernant J, Aguirre-Lamban J, Cantalapiedra D, Avila-Fernandez A, Gimenez A, Lopez-Molina MI, Garcia-Sandoval B, Blanco-Kelly F, Corton M, Tatu S, Fernandez-San Jose P, Trujillo-Tiebas MJ, Ramos C, Allikmets R, Ayuso C
Outcome of ABCA4 disease-associated alleles in autosomal recessive retinal dystrophies: retrospective analysis in 420 Spanish families.
Ophthalmology. 2013 Nov;120(11):2332-7. doi: 10.1016/j.ophtha.2013.04.002. Epub 2013 Jun 4., [PMID:23755871]

Abstract [show]
OBJECTIVE: To provide a comprehensive overview of all detected mutations in the ABCA4 gene in Spanish families with autosomal recessive retinal disorders, including Stargardt's disease (arSTGD), cone-rod dystrophy (arCRD), and retinitis pigmentosa (arRP), and to assess genotype-phenotype correlation and disease progression in 10 years by considering the type of variants and age at onset. DESIGN: Case series. PARTICIPANTS: A total of 420 unrelated Spanish families: 259 arSTGD, 86 arCRD, and 75 arRP. METHODS: Spanish families were analyzed through a combination of ABCR400 genotyping microarray, denaturing high-performance liquid chromatography, and high-resolution melting scanning. Direct sequencing was used as a confirmation technique for the identified variants. Screening by multiple ligation probe analysis was used to detect possible large deletions or insertions in the ABCA4 gene. Selected families were analyzed further by next generation sequencing. MAIN OUTCOME MEASURES: DNA sequence variants, mutation detection rates, haplotypes, age at onset, central or peripheral vision loss, and night blindness. RESULTS: Overall, we detected 70.5% and 36.6% of all expected ABCA4 mutations in arSTGD and arCRD patient cohorts, respectively. In the fraction of the cohort where the ABCA4 gene was sequenced completely, the detection rates reached 73.6% for arSTGD and 66.7% for arCRD. However, the frequency of possibly pathogenic ABCA4 alleles in arRP families was only slightly higher than that in the general population. Moreover, in some families, mutations in other known arRP genes segregated with the disease phenotype. CONCLUSIONS: An increasing understanding of causal ABCA4 alleles in arSTGD and arCRD facilitates disease diagnosis and prognosis and also is paramount in selecting patients for emerging clinical trials of therapeutic interventions. Because ABCA4-associated diseases are evolving retinal dystrophies, assessment of age at onset, accurate clinical diagnosis, and genetic testing are crucial. We suggest that ABCA4 mutations may be associated with a retinitis pigmentosa-like phenotype often as a consequence of severe (null) mutations, in cases of long-term, advanced disease, or both. Patients with classical arRP phenotypes, especially from the onset of the disease, should be screened first for mutations in known arRP genes and not ABCA4.

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88 Based on our data, the likely severe ABCA4 missense mutations, resulting in an early disease onset and severe disease, include, among others: p.Leu541Pro, p.Arg602Trp, p.Thr1019Met, p.Leu1940Pro, and p.His1838Asp. Login to comment
90 These results are supported by previous findings that the p.Leu541Pro and p.Arg602Trp variants result in mislocalized protein,22 the p.Leu1940Pro and IVS38e10T/C variants confer much earlier onset of the disease,23 and the p.His1838Asp variant, in a complex allele with the p.Gly1961Glu mutation, results in an early-onset, severe disease.24 Although the above estimates are simplified because they do not take into account environmental factors and genetic variation at other loci in these patients, they serve as a good basis for association with disease onset and disease severity. Login to comment

[hide] The clinical effect of homozygous ABCA4 alleles in... Ophthalmology. 2013 Nov;120(11):2324-31. doi: 10.1016/j.ophtha.2013.04.016. Epub 2013 Jun 12. Fujinami K, Sergouniotis PI, Davidson AE, Mackay DS, Tsunoda K, Tsubota K, Robson AG, Holder GE, Moore AT, Michaelides M, Webster AR
The clinical effect of homozygous ABCA4 alleles in 18 patients.
Ophthalmology. 2013 Nov;120(11):2324-31. doi: 10.1016/j.ophtha.2013.04.016. Epub 2013 Jun 12., [PMID:23769331]

Abstract [show]
PURPOSE: To describe the phenotypic presentation of a cohort of individuals with homozygous disease-associated ABCA4 variants. DESIGN: Retrospective case series. PARTICIPANTS: Eighteen affected individuals from 13 families ascertained from a total cohort of 214 families with ABCA4-related retinal disease presenting to a single center. METHODS: A detailed history was obtained, and color fundus photography, autofluorescence (AF) imaging, optical coherence tomography (OCT), and electrophysiologic assessment were performed. Phenotypes based on ophthalmoscopy, AF, and electrophysiology were assigned using previously reported characteristics. ABCA4 mutation detection was performed using the ABCR400 microarray (Asper Biotech, Tartu, Estonia) and high-throughput DNA sequencing, with direct sequencing used to assess segregation. MAIN OUTCOME MEASURES: Detailed clinical, electrophysiologic, and molecular genetic findings. RESULTS: Eleven disease-associated homozygous ABCA4 alleles were identified, including 1 frame shift, 2 stops, 1 intronic variant causing splice-site alteration, 2 complex missense variants, and 5 missense variants: p.Glu905fsX916, p.Arg1300X, p.Gln2220X, c.4253+4 C>T, p.Leu541Pro and p.Ala1038Val (homozygosity for complex allele), p.Val931Met and p.Arg1705Gln (complex allele), p.Arg212Cys, p.Cys1488Arg, p.Arg1640Trp, p.Gly1961Glu, and p.Leu2027Phe. Eight of these 11 homozygous alleles have not been reported previously. Six of 7 patients with homozygous null alleles had early-onset (<10 years) disease, with all 7 having a severe phenotype. Two patients with homozygous missense variants (p.Leu541Pro and p.Ala1038Val [complex], and p.Arg1640Trp) presented with a severe phenotype. Three patients with homozygous p.Gly1961Glu had adult-onset disease and a mild phenotype. One patient with homozygous p.Leu2027Phe showed a spared fovea and preserved visual acuity. CONCLUSIONS: The phenotypes represented in patients identified as homozygous for presumed disease-associated ABCA4 variants gives insight into the effect of individual alleles. Null alleles have severe functional effects, and certain missense variants are similar to nulls, suggesting complete abrogation of protein function. The common alleles identified, p.Gly1961Glu and p. Leu2027Phe, both have a mild structural and functional effect on the adult retina; the latter is associated with relatively retained photoreceptor architecture and function at the fovea.

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117 The 2 previously reported variants (p.Asn96Lys and p.His1838Asp) in complex with p.Gly1961Glu that were associated with a very severe phenotype were not detected in our patients.12 We observed a particularly late-onset mild disorder, with numerous flecks and foveal sparing, associated with p.Leu2027Phe, suggesting primary disease of the parafoveal RPE with preservation of foveal structure, a "foveal sparing" phenotype. Login to comment