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Molecular Diagnostic Testing by Eyegene: Analysis of Patients with Hereditary Retinal Dystrophy Phenotypes Involving Central Vision Loss

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Molecular Diagnostic Testing by Eyegene: Analysis of Patients with Hereditary Retinal Dystrophy Phenotypes Involving Central Vision Loss Genetics Molecular Diagnostic Testing by eyeGENE: Analysis of Patients With Hereditary Retinal Dystrophy Phenotypes Involving Central Vision Loss Akhila Alapati,1 Kerry Goetz,2 John Suk,1 Mili Navani,1 Amani Al-Tarouti,3 Thiran Jayasundera,3 Santa J. Tumminia,4 Pauline Lee,1 and Radha Ayyagari1 1Shiley Eye Center, University of California-San Diego, La Jolla, California, United States 2Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 3W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States 4Office of the Director, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States Correspondence: Radha Ayyagari, PURPOSE. To analyze the genetic test results of probands referred to eyeGENE with a diagnosis Shiley Eye Center, Jacobs Retina of hereditary maculopathy. Center,Room206,Universityof California-San Diego, 9415 Campus METHODS. Patients with Best macular dystrophy (BMD), Doyne honeycomb retinal dystrophy Point Drive, San Diego, CA 92093, (DHRD), Sorsby fundus dystrophy (SFD), or late-onset retinal degeneration (LORD) were USA; screened for mutations in BEST1, EFEMP1, TIMP3, and CTRP5, respectively. Patients with [email protected]. pattern dystrophy (PD) were screened for mutations in PRPH2, BEST1, ELOVL4, CTRP5, and Submitted: March 14, 2014 ABCA4; patients with cone-rod dystrophy (CRD) were screened for mutations in CRX, Accepted: July 18, 2014 ABCA4, PRPH2, ELOVL4, and the c.2513G>A p.Arg838His variant in GUCY2D. Mutation analysis was performed by dideoxy sequencing. Impact of novel variants was evaluated using Citation: Alapati A, Goetz K, Suk J, et al. Molecular diagnostic testing by the computational tool PolyPhen. eyeGENE: analysis of patients with RESULTS. Among the 213 unrelated patients, 38 had BMD, 26 DHRD, 74 PD, 8 SFD, 6 LORD, hereditary retinal dystrophy pheno- and 54 CRD; six had both PD and BMD, and one had no specific clinical diagnosis. BEST1 type involving central vision loss. variants were identified in 25 BMD patients, five with novel variants of unknown significance Invest Ophthalmol Vis Sci. (VUS). Among the five patients with VUS, one was diagnosed with both BMD and PD. A novel 2014;55:5510–5521. DOI:10.1167/ iovs.14-14359 EFEMP1 variant was identified in one DHRD patient. TIMP3 novel variants were found in two SFD patients, PRPH2 variants in 14 PD patients, ABCA4 variants in four PD patients, and p.Arg838His GUCY2D mutation in six patients diagnosed with dominant CRD; one patient additionally had a CRX VUS. ABCA4 mutations were identified in 15 patients with recessive CRD. CONCLUSIONS. Of the 213 samples, 55 patients (26%) had known causative mutations, and 13 (6%) patients had a VUS that was possibly pathogenic. Overall, selective screening for mutations in BEST1, PRPH2, and ABCA4 would likely yield the highest success rate in identifying the genetic basis for macular dystrophy phenotypes. Because of the overlap in phenotypes between BMD and PD, it would be beneficial to screen genes associated with both diseases. Keywords: genetic testing, eyeGENE, macular dystrophy he National Ophthalmic Disease Genotyping and Pheno- known to cause BMD2,3 (Table 1). Although BMD is an T typing Network, eyeGENE, is a multicomponent genetics autosomal dominant disease, recessive mutations in BEST1 initiative created by the National Eye Institute to facilitate are associated with recessive bestrophinopathy with symptoms research in inherited eye disease. The program provides access similar to those of dominant BMD.4 to deidentified DNA, phenotype, and genotype information of Doyne honeycomb retinal dystrophy (DHRD) or malattia its participants.1 This study describes eyeGENE data on six leventinese is clinically diagnosed by the presence of drusen in specific conditions involving central vision loss: Best macular the (sub)retinal epithelium (RPE) of the posterior region of the dystrophy, Doyne honeycomb retinal dystrophy, Sorsby fundus eye, especially in areas associated with the macula and the dystrophy, late-onset retinal degeneration, pattern dystrophy, optic disc. Over time, a honeycomb pattern of drusen and dominant and recessive cone-rod dystrophy. All of these deposition can be seen in the fundus of some patients. conditions are autosomal dominant inherited diseases except Mutations in the epidermal growth factor containing fibulin- recessive cone-rod dystrophy (CRD). like extracellular matrix protein 1 gene (EFEMP1)are Best macular dystrophy (BMD) is characterized by a yellow associated with DHRD5 (Table 1). yolk-like lesion in the macula with loss of central vision. Onset Sorsby fundus dystrophy (SFD) is a late-onset disease with of disease is generally in childhood or early teenage years. central vision loss but also includes atrophy of the peripheral Mutations in the bestrophin-1 (BEST1 or VMD2) gene are choroid, drusen-like deposits, and choroidal neovascularization Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc. www.iovs.org j ISSN: 1552-5783 5510 Downloaded from jov.arvojournals.org on 09/25/2021 Molecular Diagnostic Testing by eyeGENE IOVS j September 2014 j Vol. 55 j No. 9 j 5511 TABLE 1. Retinal Disease Genes Screened for Mutations and the Phenotypes Associated With These Genes Genes Gene Accession Screened Location Number Chromosome Associated Diagnosis ABCA4 1p22.1 NM_000350.2 1 Pattern dystrophy, cone-rod dystrophy Recessive retinitis pigmentosa BEST1 11q12.3 NM_004183.3 11 Best macular dystrophy CRX 19q13.32 19 Dominant cone-rod dystrophy CTRP5 11q23.3 NM_001278431.1 11 Late-onset retinal degeneration EFEMP1 2p16.1 NM_001039348.2 2 Doyne honeycomb retinal dystrophy ELOVL4 6q14.1 NM_022726.3 6 Autosomal dominant Stargardt’s-like macular dystrophy GUCY2D 17p13.1 NM_000180.3 17 Dominant cone-rod dystrophy PRPH2 6p21.1 NM_000322.4 6 Pattern dystrophy, cone-rod dystrophy Macular degeneration TIMP3 22q12.3 NM_000362.4 22 Sorsby fundus dystrophy in most cases.6 Mutations in the tissue inhibitor of metal- Two hundred thirteen patients listed in the eyeGENE lopeptidase 3 gene (TIMP3) have been implicated in the database with a retinal dystrophy phenotype of central vision development of SFD7 (Table 1). Due to the late age of onset, loss were selected for this study. Mutation screening was overlap in clinical symptoms, and lack of information on carried out by arrayed primer extension (APEX) technology additional family members, SFD is often misdiagnosed as the and/or dideoxy sequencing by eyeGENE collaborating labora- more common condition, age-related macular degeneration tories including ours (Downs CA, et al. IOVS 2004;45:E- (AMD). Abstract 2474). The genes selected for analysis were based on Late-onset retinal degeneration (LORD) is a disease with the primary and secondary diagnosis provided by the early onset of abnormal lens zonules, abnormalities in dark physician. When mutations were not detected in genes adaptation, late-onset drusen-like deposits, central vision loss, associated with the primary diagnosis, other genes associated and neovascularization of the retina.8 A single missense with similar phenotypes were tested. Patients with a primary mutation, p.Ser163Arg, in the C1q tumor necrosis factor- diagnosis of Stargardt’s were not included in the study. related protein 5 gene (CqQTNF5/CTRP5) has been reported in patients with LORD9 (Table 1). The clinical symptoms of Late-Onset Retinal Dystrophy LORD overlap with the symptoms of SFD and AMD. Pattern dystrophy (PD) patients often exhibit yellow, Six probands with a primary diagnosis of LORD were screened orange, or gray deposits in the macula that disrupt central for mutations in exons 1 to 3 of the CTRP5 gene. vision. Occasionally, the pattern will appear in the shape of a butterfly.10 Mutations in the peripherin 2 (PRPH2)and Sorsby Fundus Dystrophy adenosine triphosphate (ATP) binding cassette subfamily A, Eight probands with a primary diagnosis for SFD were member 4 (ABCA4) genes have been reported in patients with screened for mutations in exons 1 to 5 of the TIMP3 gene. the PD phenotype10 (Table 1). Cone-rod dystrophies are characterized by peripheral vision loss along with central vision loss, and this phenotype is Doyne Honeycomb Retinal Dystrophy inherited in both dominant and recessive fashion. Dominant Twenty-six probands with a primary diagnosis for DHRD were CRD is caused by mutations in the guanylate cyclase 2D screened for mutations in the EFEMP1 gene (exons 1–11 in 25 11–13 (GUCY2D) and the cone-rod homeobox (CRX) genes patients; exons 3–12 in one patient). (Table 1). Mutations changing the codon arginine at amino acid position 838 to histidine, proline, or cysteine in GUCY2D Best Macular Dystrophy have been identified in unrelated patients with CRD. The p.Arg828His mutation is the most common among all GUCY2D Forty-four probands with a clinical diagnosis of BMD were mutations.13 Recessive CRD is usually associated with missense screened for mutations in the BEST1 gene (exons 2–11 in 40 mutations in ABCA4.14 families; exons 1–11 in 5 families). We summarize the genetic variations identified in 213 patients from the eyeGENE database with a retinal dystrophy Pattern Dystrophy phenotype involving central vision loss. Eighty probands with a clinical diagnosis for PD were screened for mutations in the PRPH2 gene. METHODS Twenty-seven probands also had clinical signs consistent with Stargardt’s disease (STGD1), BMD, SFD, DHRD, or other Since genetic and phenotypic heterogeneity
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