51
|
Mahroo OA, Fujinami K, Moore AT, Webster AR. Retinal findings in a patient with mutations in ABCC6 and ABCA4. Eye (Lond) 2018; 32:1542-1543. [PMID: 29765157 DOI: 10.1038/s41433-018-0106-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 04/16/2018] [Indexed: 11/09/2022] Open
Affiliation(s)
- Omar A Mahroo
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital, 162 City Road, London, EC1V 2PD, UK.,Department of Ophthalmology, King's College London, St Thomas' Hospital Campus, Westminster Bridge Road, London, SE1 7EH, UK
| | - Kaoru Fujinami
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital, 162 City Road, London, EC1V 2PD, UK.,National Institute of Sensory Organs, Tokyo, Japan
| | - Anthony T Moore
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital, 162 City Road, London, EC1V 2PD, UK.,Department of Ophthalmology, UCSF School of Medicine, San Francisco, CA, 94143, USA
| | - Andrew R Webster
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK. .,Moorfields Eye Hospital, 162 City Road, London, EC1V 2PD, UK.
| |
Collapse
|
52
|
Mutation Spectrum of the ABCA4 Gene in a Greek Cohort with Stargardt Disease: Identification of Novel Mutations and Evidence of Three Prevalent Mutated Alleles. J Ophthalmol 2018; 2018:5706142. [PMID: 29854428 PMCID: PMC5952432 DOI: 10.1155/2018/5706142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/15/2018] [Indexed: 11/18/2022] Open
Abstract
Aim To evaluate the frequency and pattern of disease-associated mutations of ABCA4 gene among Greek patients with presumed Stargardt disease (STGD1). Materials and Methods A total of 59 patients were analyzed for ABCA4 mutations using the ABCR400 microarray and PCR-based sequencing of all coding exons and flanking intronic regions. MLPA analysis as well as sequencing of two regions in introns 30 and 36 reported earlier to harbor deep intronic disease-associated variants was used in 4 selected cases. Results An overall detection rate of at least one mutant allele was achieved in 52 of the 59 patients (88.1%). Direct sequencing improved significantly the complete characterization rate, that is, identification of two mutations compared to the microarray analysis (93.1% versus 50%). In total, 40 distinct potentially disease-causing variants of the ABCA4 gene were detected, including six previously unreported potentially pathogenic variants. Among the disease-causing variants, in this cohort, the most frequent was c.5714+5G>A representing 16.1%, while p.Gly1961Glu and p.Leu541Pro represented 15.2% and 8.5%, respectively. Conclusions By using a combination of methods, we completely molecularly diagnosed 48 of the 59 patients studied. In addition, we identified six previously unreported, potentially pathogenic ABCA4 mutations.
Collapse
|
53
|
Schroeder M, Kjellström U. Full-field ERG as a predictor of the natural course of ABCA4-associated retinal degenerations. Mol Vis 2018; 24:1-16. [PMID: 29386879 PMCID: PMC5757858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 01/02/2018] [Indexed: 12/03/2022] Open
Abstract
PURPOSE To assess retinal function in combination with the retinal structure in ABCA4-associated retinal degenerations. Moreover, to evaluate the possibility of predicting the natural course of these disorders. METHODS 34 patients with Stargardt disease or cone rod dystrophy carrying confirmed mutations in ABCA4 were selected from our retinitis pigmentosa (RP) register. Sequence analysis of the entire coding region of the ABCA4 gene was performed. The patients were subdivided into three groups based on their most recent visual fields. Group 1 included ten patients with central scotomas within 10°, group 2 included 19 patients with larger central scotomas of 10-35°, and group 3 included five patients with mere temporal residues. The patients underwent slit-lamp and fundus examinations, visual acuity testing, optical coherence tomography (OCT), fundus photography (color, red-free, and autofluorescence (AF) images), full-field electroretinography (ffERG), and multifocal electroretinography (mERG). FfERG and mERG results were analyzed statistically. Total rod and cone function, as well as macular function, was compared between the three groups and of each group to a normal material. In 23 patients who had undergone ffERG on a previous occasion, the 30 Hz flicker implicit time (IT) from the first visit was also analyzed. RESULTS The ffERG statistics revealed significant differences between the groups regarding cone and rod function with group 1 showing the highest amplitudes and the shortest ITs while group 3 demonstrated the lowest amplitudes and the most delayed ITs. When compared to controls, group 1 did not show any significant changes while groups 2 and 3 demonstrated reduced amplitudes and delayed 30 Hz ITs. Regarding estimation of the natural course, identical results of the 30 Hz IT were encountered for the groups also at the first visit early in the course of disease. Comparison of the mERGs showed significant differences with group 1 demonstrating the highest amplitudes and group 3 the lowest for all rings but rings 2 and 3 in the right eye for which the amplitudes were the second highest. The mERGs for each group were also compared to controls showing reduced mERG amplitudes for all rings in all groups, except group 1, left eye. OCT showed macular attenuation in all patients. Evaluation of the inner and outer photoreceptor junction (IS/OS) morphology revealed alterations related to macular function measured with mERG in all eyes. Eight patients in group 1 showed foveal IS/OS junction loss, one had foveal IS/OS junction disorganization, and one had IS/OS loss also beyond the fovea. In group 2, one patient had IS/OS junction loss confined to the fovea, and the rest showed total loss of IS/OS junctions. Group 3 was devoid of IS/OS junctions. Concerning the AF images, group 1 showed small areas of absent AF in the macula, peripapillary sparing, and flecks of increased and reduced AF in the posterior pole. In group 2, the central areas of absent AF were larger. Flecks of reduced AF were the most dominant and reached beyond the posterior pole. Seven of 19 patients had peripapillary sparing. In group 3, large confluent areas of reduced AF were found in the posterior pole and beyond with small areas of increased AF in the far periphery. No peripapillary sparing was seen. CONCLUSIONS The current study demonstrates a significant difference in total retinal function, as well as macular function, between patients with ABCA4-associated retinal degeneration and a different degree of visual field defects with gradual deterioration of function along with increased visual field constriction. Likewise, the morphological changes, including the deviant AF pattern and loss of IS/OS junctions, that were related to macular function measured with mERG worsened with the degree of visual field defects. Moreover, in these groups of patients with ABCA4-associated retinal degenerations, full-field cone 30 Hz flicker IT seems to be a predictor of the natural course of the disease also on long-term follow-up.
Collapse
|
54
|
Jimenez-Rolando B, Noval S, Rosa-Perez I, Mata Diaz E, Del Pozo A, Ibañez C, Silla JC, Montaño VEF, Martin-Arenas R, Vallespin E. Next generation sequencing in the diagnosis of Stargardt's disease. ACTA ACUST UNITED AC 2017; 93:119-125. [PMID: 28571903 DOI: 10.1016/j.oftal.2017.03.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 03/22/2017] [Accepted: 03/28/2017] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Stargardt's disease is the most frequent form of inherited macular dystrophy in children and adults. It is a genetic eye disorder caused by mutations in ABCA4 gene with an autosomal recessive inheritance. ABCA4 is a very polymorphic and large gene containing 50 exons. The development of next generation sequencing (NGS) can be used for the genetic diagnosis of this disease. PATIENTS AND METHODS A report is presented on two patients with a clinical diagnosis of Stargardt's disease whose genetic confirmation was performed by a NGS panel of 298 genes. RESULTS Clinically, the patients showed bull's eye maculopathy and absence of flecks, and genetically they shared the Gly1961Glu mutation that could explain their common phenotype, together with c.C3056T:p.T1019M for case 1, and c.287del:p.Asn96Thrfs*19 for case 2. CONCLUSIONS NGS is particularly useful in the diagnosis of Stargardt's disease as ABCA4 is a large gene with a high allelic heterogeneity that causes a wide range of clinical manifestations.
Collapse
Affiliation(s)
- B Jimenez-Rolando
- Servicio Oftalmología, Hospital Central de la Cruz Roja, Madrid, España.
| | - S Noval
- Servicio Oftalmología, IdiPAZ, Hospital Universitario La Paz, Madrid, España
| | - I Rosa-Perez
- Servicio Oftalmología, IdiPAZ, Hospital Universitario La Paz, Madrid, España
| | - E Mata Diaz
- Servicio Oftalmología, Hospital Central de la Cruz Roja, Madrid, España
| | - A Del Pozo
- Sección de Bioinformática, Servicio Genética INGEMM-IdiPAZ-CIBERER, Hospital Universitario La Paz, Madrid, España
| | - C Ibañez
- Sección de Bioinformática, Servicio Genética INGEMM-IdiPAZ-CIBERER, Hospital Universitario La Paz, Madrid, España
| | - J C Silla
- Sección de Bioinformática, Servicio Genética INGEMM-IdiPAZ-CIBERER, Hospital Universitario La Paz, Madrid, España
| | - V E F Montaño
- Sección de Genómica Estructural y Funcional, Servicio Genética INGEMM-IdiPAZ-CIBERER, Hospital Universitario La Paz, Madrid, España
| | - R Martin-Arenas
- Sección de Genómica Estructural y Funcional, Servicio Genética INGEMM-IdiPAZ-CIBERER, Hospital Universitario La Paz, Madrid, España
| | - E Vallespin
- Sección de Genómica Estructural y Funcional, Servicio Genética INGEMM-IdiPAZ-CIBERER, Hospital Universitario La Paz, Madrid, España
| |
Collapse
|
55
|
Zernant J, Lee W, Collison FT, Fishman GA, Sergeev YV, Schuerch K, Sparrow JR, Tsang SH, Allikmets R. Frequent hypomorphic alleles account for a significant fraction of ABCA4 disease and distinguish it from age-related macular degeneration. J Med Genet 2017; 54:404-412. [PMID: 28446513 DOI: 10.1136/jmedgenet-2017-104540] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 02/28/2017] [Accepted: 03/07/2017] [Indexed: 12/24/2022]
Abstract
BACKGROUND Variation in the ABCA4 gene is causal for, or associated with, a wide range of phenotypes from early onset Mendelian retinal dystrophies to late-onset complex disorders such as age-related macular degeneration (AMD). Despite substantial progress in determining the causal genetic variation, even complete sequencing of the entire open reading frame and splice sites of ABCA4 identifies biallelic mutations in only 60%-70% of cases; 20%-25% remain with one mutation and no mutations are found in 10%-15% of cases with clinically confirmed ABCA4 disease. This study was designed to identify missing causal variants specifically in monoallelic cases of ABCA4 disease. METHODS Direct sequencing and analysis were performed in a large familial ABCA4 disease cohort of predominately European descent (n=643). Patient phenotypes were assessed from clinical and retinal imaging data. RESULTS We determined that a hypomorphic ABCA4 variant c.5603A>T (p.Asn1868Ile), previously considered benign due to high minor allele frequency (MAF) (~7%) in the general population, accounts for 10% of the disease, >50% of the missing causal alleles in monoallelic cases, ~80% of late-onset cases and distinguishes ABCA4 disease from AMD. It results in a distinct clinical phenotype characterised by late-onset of symptoms (4th decade) and foveal sparing (85%). Intragenic modifying effects involving this variant and another, c.2588G>C (p.Gly863Ala) allele, were also identified. CONCLUSIONS These findings substantiate the causality of frequent missense variants and their phenotypic outcomes as a significant contribution to ABCA4 disease, particularly the late-onset phenotype, and its clinical variation. They also suggest a significant revision of diagnostic screening and assessment of ABCA4 variation in aetiology of retinal diseases.
Collapse
Affiliation(s)
- Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York, USA
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York, USA
| | - Frederick T Collison
- The Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse, Chicago, Illinois, USA
| | - Gerald A Fishman
- The Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse, Chicago, Illinois, USA
| | - Yuri V Sergeev
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kaspar Schuerch
- Department of Ophthalmology, Columbia University, New York, New York, USA
| | - Janet R Sparrow
- Department of Ophthalmology, Columbia University, New York, New York, USA.,Department of Pathology & Cell Biology, Columbia University, New York, New York, USA
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York, USA.,Department of Pathology & Cell Biology, Columbia University, New York, New York, USA
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York, USA.,Department of Pathology & Cell Biology, Columbia University, New York, New York, USA
| |
Collapse
|
56
|
Biswas P, Duncan JL, Maranhao B, Kozak I, Branham K, Gabriel L, Lin JH, Barteselli G, Navani M, Suk J, Parke M, Schlechter C, Weleber RG, Heckenlively JR, Dagnelie G, Lee P, Riazuddin SA, Ayyagari R. Genetic analysis of 10 pedigrees with inherited retinal degeneration by exome sequencing and phenotype-genotype association. Physiol Genomics 2017; 49:216-229. [PMID: 28130426 PMCID: PMC5407181 DOI: 10.1152/physiolgenomics.00096.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/31/2022] Open
Abstract
Our purpose was to identify causative mutations and characterize the phenotype associated with the genotype in 10 unrelated families with autosomal recessive retinal degeneration. Ophthalmic evaluation and DNA isolation were carried out in 10 pedigrees with inherited retinal degenerations (IRD). Exomes of probands from eight pedigrees were captured using Nimblegen V2/V3 or Agilent V5+UTR kits, and sequencing was performed on Illumina HiSeq. The DHDDS gene was screened for mutations in the remaining two pedigrees with Ashkenazi Jewish ancestry. Exome variants were filtered to detect candidate causal variants using exomeSuite software. Segregation and ethnicity-matched control sample analysis were performed by dideoxy sequencing. Retinal histology of a patient with DHDDS mutation was studied by microscopy. Genetic analysis identified six known mutations in ABCA4 (p.Gly1961Glu, p.Ala1773Val, c.5461-10T>C), RPE65 (p.Tyr249Cys, p.Gly484Asp), PDE6B (p.Lys706Ter) and DHDDS (p.Lys42Glu) and ten novel potentially pathogenic variants in CERKL (p.Met323Val fsX20), RPE65 (p.Phe252Ser, Thr454Leu fsX31), ARL6 (p.Arg121His), USH2A (p.Gly3142Ter, p.Cys3294Trp), PDE6B (p.Gln652Ter), and DHDDS (p.Thr206Ala) genes. Among these, variants/mutations in two separate genes were observed to segregate with IRD in two pedigrees. Retinal histopathology of a patient with a DHDDS mutation showed severe degeneration of retinal layers with relative preservation of the retinal pigment epithelium. Analysis of exome variants in ten pedigrees revealed nine novel potential disease-causing variants and nine previously reported homozygous or compound heterozygous mutations in the CERKL, ABCA4, RPE65, ARL6, USH2A, PDE6B, and DHDDS genes. Mutations that could be sufficient to cause pathology were observed in more than one gene in one pedigree.
Collapse
Affiliation(s)
- Pooja Biswas
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | - Jacque L Duncan
- Ophthalmology, University of California San Francisco, San Francisco, California
| | - Bruno Maranhao
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | - Igor Kozak
- King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Kari Branham
- Ophthalmology & Visual Science, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan
| | - Luis Gabriel
- Genetics and Ophthalmology, Genelabor, Goiânia, Brazil
| | - Jonathan H Lin
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | - Giulio Barteselli
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | - Mili Navani
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | - John Suk
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | - Michelle Parke
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | | | - Richard G Weleber
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon; and
| | - John R Heckenlively
- Ophthalmology & Visual Science, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan
| | - Gislin Dagnelie
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Pauline Lee
- Shiley Eye Institute, University of California San Diego, La Jolla, California
| | - S Amer Riazuddin
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Radha Ayyagari
- Shiley Eye Institute, University of California San Diego, La Jolla, California;
| |
Collapse
|
57
|
Tanna P, Strauss RW, Fujinami K, Michaelides M. Stargardt disease: clinical features, molecular genetics, animal models and therapeutic options. Br J Ophthalmol 2016; 101:25-30. [PMID: 27491360 PMCID: PMC5256119 DOI: 10.1136/bjophthalmol-2016-308823] [Citation(s) in RCA: 218] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/20/2016] [Accepted: 07/11/2016] [Indexed: 01/07/2023]
Abstract
Stargardt disease (STGD1; MIM 248200) is the most prevalent inherited macular dystrophy and is associated with disease-causing sequence variants in the gene ABCA4. Significant advances have been made over the last 10 years in our understanding of both the clinical and molecular features of STGD1, and also the underlying pathophysiology, which has culminated in ongoing and planned human clinical trials of novel therapies. The aims of this review are to describe the detailed phenotypic and genotypic characteristics of the disease, conventional and novel imaging findings, current knowledge of animal models and pathogenesis, and the multiple avenues of intervention being explored.
Collapse
Affiliation(s)
- Preena Tanna
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital, London, UK
| | - Rupert W Strauss
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital, London, UK.,Departments of Ophthalmology, Medical University Graz and Johannes Kepler University, Linz, Austria
| | - Kaoru Fujinami
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital, London, UK.,National Institute of Sensory Organs, National Hospital Organization, Tokyo Medical Centre, Tokyo, Japan
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital, London, UK
| |
Collapse
|
58
|
Genomic screening of ABCA4 and array CGH analysis underline the genetic variability of Greek patients with inherited retinal diseases. Meta Gene 2016; 8:37-43. [PMID: 27014590 PMCID: PMC4792891 DOI: 10.1016/j.mgene.2016.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 01/12/2016] [Accepted: 02/10/2016] [Indexed: 11/22/2022] Open
Abstract
Background Retinal dystrophies are a clinically and genetically heterogeneous group of disorders which affect more than two million people worldwide. The present study focused on the role of the ABCA4 gene in the pathogenesis of hereditary retinal dystrophies (autosomal recessive Stargardt disease, autosomal recessive cone-rod dystrophy, and autosomal recessive retinitis pigmentosa) in patients of Greek origin. Materials and methods Our cohort included 26 unrelated patients and their first degree healthy relatives. The ABCA4 mutation screening involved Sanger sequencing of all exons and flanking regions. Evaluation of novel variants included sequencing of control samples, family segregation analysis and characterization by in silico prediction tools. Twenty five patients were also screened for copy number variations by array-comparative genomic hybridization. Results Excluding known disease-causing mutations and polymorphisms, two novel variants were identified in coding and non-coding regions of ABCA4. Array-CGH analysis revealed two partial deletions of USH2A and MYO3A in two patients with nonsyndromic autosomal recessive retinitis pigmentosa. Conclusions The ABCA4 mutation spectrum in Greek patients differs from other populations. Bioinformatic tools, segregation analysis along with clinical data from the patients seemed to be crucial for the evaluation of genetic variants and particularly for the discrimination between causative and non-causative variants. Sixteen known pathological genetic variants were identified in ABCA4 gene in Greek patients with retinal dystrophies. Two novel variants were found in patients with Stargardt’s disease and cone-rod dystrophy respectively. Two reported mutations in Stargardt's patients were identified in retinitis pigmentosa and cone-rod dystrophy patients. The mutations p.Gly1961Glu and p.Ala1038Val, which are common in other populations, where also found in our cohort consisted of 26 Greek patients. Array-comparative genome hybridization revealed large deletions in two out of the 25 cases studied.
Collapse
|
59
|
Complex inheritance of ABCA4 disease: four mutations in a family with multiple macular phenotypes. Hum Genet 2015; 135:9-19. [PMID: 26527198 DOI: 10.1007/s00439-015-1605-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 10/01/2015] [Indexed: 01/12/2023]
Abstract
Over 800 mutations in the ABCA4 gene cause autosomal recessive Stargardt disease. Due to extensive genetic heterogeneity, observed variant-associated phenotypes can manifest tremendous variability of expression. Furthermore, the high carrier frequency of pathogenic ABCA4 alleles in the general population (~1:20) often results in pseudo-dominant inheritance patterns further complicating the diagnosis and characterization of affected individuals. This study describes a genotype/phenotype analysis of an unusual family with multiple macular disease phenotypes spanning across two generations and segregating four distinct ABCA4 mutant alleles. Complete sequencing of ABCA4 discovered two known missense mutations, p.C54Y and p.G1961E. Array comparative genomic hybridization revealed a large novel deletion combined with a small insertion, c.6148-698_c.6670del/insTGTGCACCTCCCTAG, and complete sequencing of the entire ABCA4 genomic locus uncovered a new deep intronic variant, c.302+68C>T. Patients with the p.G1961E mutation had the mildest, confined maculopathy phenotype with peripheral flecks while those with all other mutant allele combinations exhibited a more advanced stage of generalized retinal and choriocapillaris atrophy. This family epitomizes the clinical and genetic complexity of ABCA4-associated diseases. It contained variants from all classes of mutations, in the coding region, deep intronic, both single nucleotide variants and copy number variants that accounted for varying phenotypes segregating in an apparent dominant fashion. Unequivocally defining disease-associated alleles in the ABCA4 locus requires a multifaceted approach that includes advanced mutation detection methods and a thorough analysis of clinical phenotypes.
Collapse
|
60
|
Bax NM, Sangermano R, Roosing S, Thiadens AAHJ, Hoefsloot LH, van den Born LI, Phan M, Klevering BJ, Westeneng-van Haaften C, Braun TA, Zonneveld-Vrieling MN, de Wijs I, Mutlu M, Stone EM, den Hollander AI, Klaver CCW, Hoyng CB, Cremers FPM. Heterozygous deep-intronic variants and deletions in ABCA4 in persons with retinal dystrophies and one exonic ABCA4 variant. Hum Mutat 2015; 36:43-7. [PMID: 25363634 DOI: 10.1002/humu.22717] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 10/18/2014] [Indexed: 11/05/2022]
Abstract
Variants in ABCA4 are responsible for autosomal-recessive Stargardt disease and cone-rod dystrophy. Sequence analysis of ABCA4 exons previously revealed one causative variant in each of 45 probands. To identify the "missing" variants in these cases, we performed multiplex ligation-dependent probe amplification-based deletion scanning of ABCA4. In addition, we sequenced the promoter region, fragments containing five deep-intronic splice variants, and 15 deep-intronic regions containing weak splice sites. Heterozygous deletions spanning ABCA4 exon 5 or exons 20-22 were found in two probands, heterozygous deep-intronic variants were identified in six probands, and a deep-intronic variant was found together with an exon 20-22 deletion in one proband. Based on ophthalmologic findings and characteristics of the identified exonic variants present in trans, the deep-intronic variants V1 and V4 were predicted to be relatively mild and severe, respectively. These findings are important for proper genetic counseling and for the development of variant-specific therapies.
Collapse
Affiliation(s)
- Nathalie M Bax
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
61
|
Zernant J, Collison FT, Lee W, Fishman GA, Noupuu K, Yuan B, Cai C, Lupski JR, Yannuzzi LA, Tsang SH, Allikmets R. Genetic and clinical analysis of ABCA4-associated disease in African American patients. Hum Mutat 2015; 35:1187-94. [PMID: 25066811 PMCID: PMC4283973 DOI: 10.1002/humu.22626] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/25/2014] [Indexed: 12/30/2022]
Abstract
Autosomal recessive Stargardt disease (STGD1) is caused by hundreds of mutations in the ABCA4 gene, which are often specific to racial and ethnic groups. Here, we investigated the ABCA4 variation and their phenotypic expression in a cohort of 44 patients of African American descent, a previously under-characterized racial group. Patients were screened for mutations in ABCA4 by next-generation sequencing and array-comparative genomic hybridization (aCGH), followed by analyses for pathogenicity by in silico programs. Thorough ophthalmic examination was performed on all patients. At least two (expected) disease-causing alleles in the ABCA4 gene were identified in 27 (61.4%) patients, one allele in 11 (25%) patients, and no ABCA4 mutations were found in six (13.6%) patients. Altogether, 39 different disease-causing ABCA4 variants, including seven new, were identified on 65 (74%) chromosomes, most of which were unique for this racial group. The most frequent ABCA4 mutation in this cohort was c.6320G>A (p.(R2107H)), representing 19.3% of all disease-associated alleles. No large copy number variants were identified in any patient. Most patients reported later onset of symptoms. In summary, the ABCA4 mutation spectrum in patients of West African descent differs significantly from that in patients of European descent, resulting in a later onset and "milder" disease.
Collapse
Affiliation(s)
- Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
62
|
Identification of Novel Mutations in ABCA4 Gene: Clinical and Genetic Analysis of Indian Patients with Stargardt Disease. BIOMED RESEARCH INTERNATIONAL 2015; 2015:940864. [PMID: 25922843 PMCID: PMC4398921 DOI: 10.1155/2015/940864] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 02/13/2015] [Accepted: 03/09/2015] [Indexed: 11/17/2022]
Abstract
Stargardt disease (STGD) is the leading cause of juvenile macular degeneration associated with progressive central vision loss, photophobia, and colour vision abnormalities. In this study, we have described the clinical and genetic features of Stargardt patients from an Indian cohort. The next generation sequencing was carried out in five clinically confirmed unrelated patients and their family members using a gene panel comprising 184 retinal specific genes. Sequencing results were analyzed by read mapping and variant calling in genes of interest, followed by their verification and interpretation. Genetic analysis revealed ABCA4 mutations in all of the five unrelated patients. Among these, four patients were found with compound heterozygous mutations and another one had homozygous mutation. All the affected individuals showed signs and symptoms consistent with the disease phenotype. We report two novel ABCA4 mutations in Indian patients with STGD disease, which expands the existing spectrum of disease-causing variants and the understanding of phenotypic and genotypic correlations. Screening for causative mutations in patients with STGD using panel of targeted gene sequencing by NGS would be a cost effective tool, might be helpful in confirming the precise diagnosis, and contributes towards the genetic counselling of asymptomatic carriers and isolated patients.
Collapse
|
63
|
den Hollander AI, de Jong EK. Highly penetrant alleles in age-related macular degeneration. Cold Spring Harb Perspect Med 2014; 5:a017202. [PMID: 25377141 DOI: 10.1101/cshperspect.a017202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Age-related macular degeneration (AMD) is a complex disease caused by a combination of genetic and environmental factors. Genome-wide association studies have identified several common genetic variants associated with AMD, which together account for 15%-65% of the heritability of AMD. Multiple hypotheses to clarify the unexplained portion of genetic variance have been proposed, such as gene-gene interactions, gene-environment interactions, structural variations, epigenetics, and rare variants. Several studies support a role for rare variants with large effect sizes in the pathogenesis of AMD. In this work, we review the methods that can be used to detect rare variants in common diseases, as well as the recent progress that has been made in the identification of rare variants in AMD. In addition, the relevance of these rare variants for diagnosis, prognosis, and treatment of AMD is highlighted.
Collapse
Affiliation(s)
- Anneke I den Hollander
- Department of Ophthalmology and Department of Human Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Eiko K de Jong
- Department of Ophthalmology and Department of Human Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| |
Collapse
|
64
|
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; 55:8134-43. [PMID: 25342616 DOI: 10.1167/iovs.14-14848] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Tobias Duncker
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Ophthalmology, Charité, University Medicine Berlin, Berlin, Germany
| | - Marcela Marsiglia
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology and Cell Biology, Columbia University, New York, New York, United States
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology and Cell Biology, Columbia University, New York, New York, United States
| | | | - Janet R Sparrow
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology and Cell Biology, Columbia University, New York, New York, United States
| |
Collapse
|
65
|
Nõupuu K, Lee W, Zernant J, Tsang SH, Allikmets R. Structural and genetic assessment of the ABCA4-associated optical gap phenotype. Invest Ophthalmol Vis Sci 2014; 55:7217-26. [PMID: 25301883 DOI: 10.1167/iovs.14-14674] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the developmental stages and genetic etiology of the optical gap phenotype in recessive Stargardt disease (STGD1). METHODS Single and longitudinal data points from 15 patients, including four sibling pairs, exhibiting an optical gap phenotype on spectral-domain optical coherence tomography (SD-OCT) with confirmed disease-causing ABCA4 alleles were retrospectively analyzed. Fundus images with corresponding SD-OCT scans were collected with a confocal scanning laser ophthalmoscope. Structural phenotypes were assigned to three developmental stages according to SD-OCT. The ABCA4 gene was screened in all patients. RESULTS At least two disease-causing ABCA4 variants where identified in each patient; all except one (91%) were compound heterozygous for the p.G1961E mutation. All patients exhibited structural findings on SD-OCT that grouped into three progressive developmental stages over several years. Stage 1 was characterized by mild disruptions of the ellipsoid zone (EZ) band over the fovea. Stage 2 was a progressive expansion of the EZ band loss resulting in an empty lesion devoid of photoreceptors. Stage 3 observed a structural collapse of the inner retinal layers into the optical gap space leading to involvement and atrophy of the RPE thereafter. CONCLUSIONS The optical gap phenotype in STGD1 can be structurally divided into three progressive stages spanning several years. This particular phenotype also appears to be highly associated with the p.G1961E mutation of ABCA4. Taken together, it appears that a focal loss of photoreceptors sequentially precedes RPE dysfunction in the early development of ABCA4-associated optical gap lesions.
Collapse
Affiliation(s)
- Kalev Nõupuu
- Department of Ophthalmology, Columbia University, New York, New York, United States Eye Clinic, Tartu University Hospital, Tartu, Estonia
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology & Cell Biology, Columbia University, New York, New York, United States
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology & Cell Biology, Columbia University, New York, New York, United States
| |
Collapse
|
66
|
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 2014; 122:345-55. [PMID: 25283059 DOI: 10.1016/j.ophtha.2014.08.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/26/2014] [Accepted: 08/06/2014] [Indexed: 11/30/2022] Open
Abstract
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°, 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° to 9° 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.
Collapse
Affiliation(s)
- Tobias Duncker
- Department of Ophthalmology, Columbia University, New York, New York
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York
| | - Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - François C Delori
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
| | - Janet R Sparrow
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology and Cell Biology, Columbia University, New York, New York.
| |
Collapse
|
67
|
Bonilha VL, Rayborn ME, Bell BA, Marino MJ, Fishman GA, Hollyfield JG. Retinal Histopathology in Eyes from a Patient with Stargardt disease caused by Compound Heterozygous ABCA4 Mutations. Ophthalmic Genet 2014; 37:150-60. [DOI: 10.3109/13816810.2014.958861] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Vera L. Bonilha
- Cole Eye Institute, Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA, and
| | - Mary E. Rayborn
- Cole Eye Institute, Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA, and
| | - Brent A. Bell
- Cole Eye Institute, Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA, and
| | - Meghan J. Marino
- Cole Eye Institute, Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA, and
| | - Gerald A. Fishman
- Chicago Lighthouse for People Who Are Blind or Visually Impaired, Chicago, IL, USA
| | - Joe G. Hollyfield
- Cole Eye Institute, Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA, and
| |
Collapse
|
68
|
Watson CM, El-Asrag M, Parry DA, Morgan JE, Logan CV, Carr IM, Sheridan E, Charlton R, Johnson CA, Taylor G, Toomes C, McKibbin M, Inglehearn CF, Ali M. Mutation screening of retinal dystrophy patients by targeted capture from tagged pooled DNAs and next generation sequencing. PLoS One 2014; 9:e104281. [PMID: 25133751 PMCID: PMC4136783 DOI: 10.1371/journal.pone.0104281] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 07/07/2014] [Indexed: 12/30/2022] Open
Abstract
Purpose Retinal dystrophies are genetically heterogeneous, resulting from mutations in over 200 genes. Prior to the development of massively parallel sequencing, comprehensive genetic screening was unobtainable for most patients. Identifying the causative genetic mutation facilitates genetic counselling, carrier testing and prenatal/pre-implantation diagnosis, and often leads to a clearer prognosis. In addition, in a proportion of cases, when the mutation is known treatment can be optimised and patients are eligible for enrolment into clinical trials for gene-specific therapies. Methods Patient genomic DNA was sheared, tagged and pooled in batches of four samples, prior to targeted capture and next generation sequencing. The enrichment reagent was designed against genes listed on the RetNet database (July 2010). Sequence data were aligned to the human genome and variants were filtered to identify potential pathogenic mutations. These were confirmed by Sanger sequencing. Results Molecular analysis of 20 DNAs from retinal dystrophy patients identified likely pathogenic mutations in 12 cases, many of them known and/or confirmed by segregation. These included previously described mutations in ABCA4 (c.6088C>T,p.R2030*; c.5882G>A,p.G1961E), BBS2 (c.1895G>C,p.R632P), GUCY2D (c.2512C>T,p.R838C), PROM1 (c.1117C>T,p.R373C), RDH12 (c.601T>C,p.C201R; c.506G>A,p.R169Q), RPGRIP1 (c.3565C>T,p.R1189*) and SPATA7 (c.253C>T,p.R85*) and new mutations in ABCA4 (c.3328+1G>C), CRB1 (c.2832_2842+23del), RP2 (c.884-1G>T) and USH2A (c.12874A>G,p.N4292D). Conclusions Tagging and pooling DNA prior to targeted capture of known retinal dystrophy genes identified mutations in 60% of cases. This relatively high success rate may reflect enrichment for consanguineous cases in the local Yorkshire population, and the use of multiplex families. Nevertheless this is a promising high throughput approach to retinal dystrophy diagnostics.
Collapse
Affiliation(s)
- Christopher M. Watson
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, United Kingdom
| | - Mohammed El-Asrag
- Section of Ophthalmology & Neuroscience, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - David A. Parry
- Section of Genetics, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Joanne E. Morgan
- Section of Genetics, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Clare V. Logan
- Section of Ophthalmology & Neuroscience, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Ian M. Carr
- Section of Genetics, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Eamonn Sheridan
- Section of Genetics, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Ruth Charlton
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, United Kingdom
| | - Colin A. Johnson
- Section of Ophthalmology & Neuroscience, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Graham Taylor
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, United Kingdom
| | - Carmel Toomes
- Section of Ophthalmology & Neuroscience, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Martin McKibbin
- Section of Ophthalmology & Neuroscience, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
- Department of Ophthalmology, St. James's University Hospital, Leeds, United Kingdom
| | - Chris F. Inglehearn
- Section of Ophthalmology & Neuroscience, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Manir Ali
- Section of Ophthalmology & Neuroscience, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, Leeds, United Kingdom
- * E-mail:
| |
Collapse
|
69
|
Zernant J, Xie YA, Ayuso C, Riveiro-Alvarez R, Lopez-Martinez MA, Simonelli F, Testa F, Gorin MB, Strom SP, Bertelsen M, Rosenberg T, Boone PM, Yuan B, Ayyagari R, Nagy PL, Tsang SH, Gouras P, Collison FT, Lupski JR, Fishman GA, Allikmets R. Analysis of the ABCA4 genomic locus in Stargardt disease. Hum Mol Genet 2014; 23:6797-806. [PMID: 25082829 DOI: 10.1093/hmg/ddu396] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Autosomal recessive Stargardt disease (STGD1, MIM 248200) is caused by mutations in the ABCA4 gene. Complete sequencing of ABCA4 in STGD patients identifies compound heterozygous or homozygous disease-associated alleles in 65-70% of patients and only one mutation in 15-20% of patients. This study was designed to find the missing disease-causing ABCA4 variation by a combination of next-generation sequencing (NGS), array-Comparative Genome Hybridization (aCGH) screening, familial segregation and in silico analyses. The entire 140 kb ABCA4 genomic locus was sequenced in 114 STGD patients with one known ABCA4 exonic mutation revealing, on average, 200 intronic variants per sample. Filtering of these data resulted in 141 candidates for new mutations. Two variants were detected in four samples, two in three samples, and 20 variants in two samples, the remaining 117 new variants were detected only once. Multimodal analysis suggested 12 new likely pathogenic intronic ABCA4 variants, some of which were specific to (isolated) ethnic groups. No copy number variation (large deletions and insertions) was detected in any patient suggesting that it is a very rare event in the ABCA4 locus. Many variants were excluded since they were not conserved in non-human primates, were frequent in African populations and, therefore, represented ancestral, and not disease-associated, variants. The sequence variability in the ABCA4 locus is extensive and the non-coding sequences do not harbor frequent mutations in STGD patients of European-American descent. Defining disease-associated alleles in the ABCA4 locus requires exceptionally well characterized large cohorts and extensive analyses by a combination of various approaches.
Collapse
Affiliation(s)
| | | | - Carmen Ayuso
- Department of Genetics, Instituto de Investigacion Sanitaria-University Hospital Fundacion Jimenez Diaz, UAM (IIS-FJD), Madrid, Spain Centro de Investigacion Biomedica en Red (CIBER) de Enfermedades Raras, ISCIII, Madrid, Spain
| | - Rosa Riveiro-Alvarez
- Department of Genetics, Instituto de Investigacion Sanitaria-University Hospital Fundacion Jimenez Diaz, UAM (IIS-FJD), Madrid, Spain Centro de Investigacion Biomedica en Red (CIBER) de Enfermedades Raras, ISCIII, Madrid, Spain
| | - Miguel-Angel Lopez-Martinez
- Department of Genetics, Instituto de Investigacion Sanitaria-University Hospital Fundacion Jimenez Diaz, UAM (IIS-FJD), Madrid, Spain Centro de Investigacion Biomedica en Red (CIBER) de Enfermedades Raras, ISCIII, Madrid, Spain
| | - Francesca Simonelli
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Second University of Naples, Naples, Italy
| | - Francesco Testa
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Second University of Naples, Naples, Italy
| | - Michael B Gorin
- Department of Ophthalmology Department of Human Genetics, Jules Stein Eye Institute and
| | - Samuel P Strom
- Department of Ophthalmology Department of Human Genetics, Jules Stein Eye Institute and Department of Pathology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Mette Bertelsen
- Kennedy Center Eye Clinic, Glostrup Hospital, Glostrup, Denmark
| | | | - Philip M Boone
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Bo Yuan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Radha Ayyagari
- Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA and
| | - Peter L Nagy
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Stephen H Tsang
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | | | - Frederick T Collison
- The Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse for People Who are Blind or Visually Impaired, Chicago, IL, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Gerald A Fishman
- The Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse for People Who are Blind or Visually Impaired, Chicago, IL, USA
| | - Rando Allikmets
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| |
Collapse
|
70
|
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; 55:2841-52. [PMID: 24677105 DOI: 10.1167/iovs.13-13624] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Tomas R Burke
- Department of Ophthalmology and Columbia University, New York, New York, United States
| | | | | | | | | | | | | | | | | | | |
Collapse
|
71
|
Miraldi Utz V, Coussa RG, Marino MJ, Chappelow AV, Pauer GJ, Hagstrom SA, Traboulsi EI. Predictors of visual acuity and genotype-phenotype correlates in a cohort of patients with Stargardt disease. Br J Ophthalmol 2014; 98:513-8. [DOI: 10.1136/bjophthalmol-2013-304270] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
72
|
Abstract
PURPOSE OF REVIEW An update on heritable eye disease will allow informed patient counseling and improved patient care. RECENT FINDINGS New loci and genes have been associated with identifiable heritable ocular traits. Molecular genetic analysis is available for many of these genes either as part of research or for clinical testing. The advent of gene array technologies has enabled screening of samples for known mutations in genes linked to various disorders. Exomic sequencing has proven to be particularly successful in research protocols in identifying the genetic causation of rare genetic traits by pooling patient resources and discovering new genes. Further, genetic analysis has led improvement in patient care and counselling, as exemplified by the continued advances in our treatment of retinoblastoma. SUMMARY Patients and families are commonly eager to participate in either research or clinical testing to improve their understanding of the cause and heritability of an ocular condition. Many patients hope that testing will then lead to appropriate treatments or cures. The success of gene therapy in the RPE65 form of Leber congenital amaurosis has provided a brilliant example of this hope; that a similar trial may become available to other patients and families burdened by genetic disease.
Collapse
|
73
|
Utz VM, Chappelow AV, Marino MJ, Beight CD, Sturgill-Short GM, Pauer GJT, Crowe S, Hagstrom SA, Traboulsi EI. Identification of three ABCA4 sequence variations exclusive to African American patients in a cohort of patients with Stargardt disease. Am J Ophthalmol 2013; 156:1220-1227.e2. [PMID: 24011517 DOI: 10.1016/j.ajo.2013.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 11/18/2022]
Abstract
PURPOSE To describe the clinical and molecular findings in ten unrelated African American patients with Stargardt disease. DESIGN Retrospective, observational case series. METHODS We reviewed the clinical histories, examinations, and genotypes of 85 patients with molecular diagnoses of Stargardt disease. Three ABCA4 sequence variations identified exclusively in African Americans were evaluated in 300 African American controls and by in silico analysis. RESULTS ABCA4 sequence changes were identified in 85 patients from 80 families, of which 11 patients identified themselves as African American. Of these 11 patients, 10 unrelated patients shared 1 of 3 ABCA4 sequence variations: c.3602T>G (p.L1201R); c.3899G>A (p.R1300Q); or c.6320G>A (p.R2107H). The minor allele frequencies in the African American control population for each variation were 7.5%, 6.3%, and 2%, respectively. This is comparable to the allele frequency in African Americans in the Exome Variant Server. In contrast, the allele frequency of all three of these variations was less than or equal to 0.05% in European Americans. Although both c.3602T>G and c.3899G>A have been reported as likely disease-causing variations, one of our control patients was homozygous for each variant, suggesting that these are nonpathogenic. In contrast, the absence of c.6320G>A in the control population in the homozygous state, combined with the results of bioinformatics analysis, support its pathogenicity. CONCLUSIONS Three ABCA4 sequence variations were identified exclusively in 10 unrelated African American patients: p.L1201R and p.R1300Q likely represent nonpathogenic sequence variants, whereas the p.R2107H substitution appears to be pathogenic. Characterization of population-specific disease alleles may have important implications for the development of genetic screening algorithms.
Collapse
|
74
|
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; 156:487-501.e1. [PMID: 23953153 DOI: 10.1016/j.ajo.2013.05.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/06/2013] [Accepted: 05/06/2013] [Indexed: 12/25/2022]
Abstract
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 μm (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.
Collapse
Affiliation(s)
- Kaoru Fujinami
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom; Laboratory of Visual Physiology, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan; Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan
| | - Panagiotis I Sergouniotis
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Alice E Davidson
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Genevieve Wright
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Ravinder K Chana
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Kazushige Tsunoda
- Laboratory of Visual Physiology, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan
| | - Kazuo Tsubota
- Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan
| | - Catherine A Egan
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Anthony G Robson
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Anthony T Moore
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Graham E Holder
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Michel Michaelides
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Andrew R Webster
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom.
| |
Collapse
|
75
|
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; 120:2324-31. [PMID: 23769331 DOI: 10.1016/j.ophtha.2013.04.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/17/2013] [Accepted: 04/17/2013] [Indexed: 10/26/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Kaoru Fujinami
- UCL Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom; National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan; Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
76
|
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; 120:2332-7. [PMID: 23755871 DOI: 10.1016/j.ophtha.2013.04.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/03/2013] [Accepted: 04/03/2013] [Indexed: 10/26/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Rosa Riveiro-Alvarez
- Department of Genetics, Instituto de Investigacion Sanitaria-Fundacion Jimenez Diaz (IIS-FJD), Madrid, Spain; Centro de Investigacion Biomedica en Red (CIBER) de Enfermedades Raras, ISCIII, Madrid, Spain
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|