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Lassen FH, Venkatesh SS, Baya N, Zhou W, Bloemendal A, Neale BM, Kessler BM, Whiffin N, Lindgren CM, Palmer DS. Exome-wide evidence of compound heterozygous effects across common phenotypes in the UK Biobank. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.06.29.23291992. [PMID: 37461573 PMCID: PMC10350147 DOI: 10.1101/2023.06.29.23291992] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Exome-sequencing association studies have successfully linked rare protein-coding variation to risk of thousands of diseases. However, the relationship between rare deleterious compound heterozygous (CH) variation and their phenotypic impact has not been fully investigated. Here, we leverage advances in statistical phasing to accurately phase rare variants (MAF ~ 0.001%) in exome sequencing data from 175,587 UK Biobank (UKBB) participants, which we then systematically annotate to identify putatively deleterious CH coding variation. We show that 6.5% of individuals carry such damaging variants in the CH state, with 90% of variants occurring at MAF < 0.34%. Using a logistic mixed model framework, systematically accounting for relatedness, polygenic risk, nearby common variants, and rare variant burden, we investigate recessive effects in common complex diseases. We find six exome-wide significant (P < 1.68 × 10 - 7 ) and 17 nominally significant (P < 5.25 × 10 - 5 ) gene-trait associations. Among these, only four would have been identified without accounting for CH variation in the gene. We further incorporate age-at-diagnosis information from primary care electronic health records, to show that genetic phase influences lifetime risk of disease across 20 gene-trait combinations (FDR < 5%). Using a permutation approach, we find evidence for genetic phase contributing to disease susceptibility for a collection of gene-trait pairs, including FLG-asthma (P = 0.00205 ) and USH2A-visual impairment (P = 0.0084 ). Taken together, we demonstrate the utility of phasing large-scale genetic sequencing cohorts for robust identification of the phenome-wide consequences of compound heterozygosity.
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Affiliation(s)
- Frederik H. Lassen
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Samvida S. Venkatesh
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Nikolas Baya
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Wei Zhou
- Program in Medical and Population Genetics Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Analytical and Translational Genetics Unit, Department of Medicine Massachusetts General Hospital, Boston, MA, USA
| | - Alex Bloemendal
- Program in Medical and Population Genetics Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Novo Nordisk Center for Genomic Mechanisms of Disease Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Data Sciences Platform Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Benjamin M. Neale
- Program in Medical and Population Genetics Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Stanley Center for Psychiatric Research Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Analytical and Translational Genetics Unit, Department of Medicine Massachusetts General Hospital, Boston, MA, USA
| | - Benedikt M. Kessler
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicola Whiffin
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
- Program in Medical and Population Genetics Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Cecilia M. Lindgren
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
- Nuffield Department of Population Health Health, Medical Sciences Division University of Oxford, Oxford, United Kingdom
| | - Duncan S. Palmer
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
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Yu D, Zou J, Chen Q, Zhu T, Sui R, Yang J. Structural modeling, mutation analysis, and in vitro expression of usherin, a major protein in inherited retinal degeneration and hearing loss. Comput Struct Biotechnol J 2020; 18:1363-1382. [PMID: 32637036 PMCID: PMC7317166 DOI: 10.1016/j.csbj.2020.05.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 11/15/2022] Open
Abstract
Usherin is the most common causative protein associated with autosomal recessive retinitis pigmentosa (RP) and Usher syndrome (USH), which are characterized by retinal degeneration alone and in combination with hearing loss, respectively. Usherin is essential for photoreceptor survival and hair cell bundle integrity. However, the molecular mechanism underlying usherin function in normal and disease conditions is unclear. In this study, we investigated structural models of usherin domains and localization of usherin pathogenic small in-frame mutations, mainly homozygous missense mutations. We found that usherin fibronectin III (FN3) domains and most laminin-related domains have a β-sandwich structure. Some FN3 domains are predicted to interact with each other and with laminin-related domains. The usherin protein may bend at some FN3 linker regions. RP- and USH-associated small in-frame mutations are differentially located in usherin domains. Most of them are located at the periphery of β-sandwiches, with some at the interface between interacting domains. The usherin laminin epidermal growth factor repeats adopt a rod-shaped structure, which is maintained by disulfide bonds. Most missense mutations and deletion of exon 13 in this region disrupt the disulfide bonds and may affect local protein folding. Despite low expression of the recombinant entire protein and protein fragments in mammalian cell culture, usherin FN3 fragments are more robustly expressed and secreted than its laminin-related fragments. Our findings provide new insights into the usherin structure and the disease mechanisms caused by pathogenic small in-frame mutations, which will help inform future experimental research on diagnosis, disease mechanisms, and therapeutic approaches.
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Key Words
- Cell adhesion
- DCC, deleted in colorectal cancer
- FN3, fibronectin III
- GMQE, global quality estimation score
- HGMD, Human Gene Mutation Database
- Hair cell
- I-TASSER, Iterative Threading ASSEmbly Refinement
- LE, laminin EGF
- LG, laminin globular
- LGL, laminin globular-like
- LN, laminin N-terminal
- Membrane protein
- NCBI, National Center for Biotechnology Information
- Photoreceptor
- Protein folding
- QMEAN, qualitative model energy analysis score
- QSQE, Quaternary Structure Quality Estimation
- RMSD, root mean square deviation
- RP, retinitis pigmentosa
- Recombinant protein expression
- Retinitis pigmentosa
- SMTL, SWISS-MODEL template library
- Structural model
- TM-score, template modeling score
- USH, Usher syndrome
- Usher syndrome
- hFc, human Fc fragment
- mFc, mouse Fc fragment
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Affiliation(s)
- Dongmei Yu
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT, United States
| | - Junhuang Zou
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT, United States
| | - Qian Chen
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT, United States
| | - Tian Zhu
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Ruifang Sui
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT, United States
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, United States
- Division of Otolaryngology, Department of Surgery, University of Utah, Salt Lake City, UT, United States
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He C, Liu X, Zhong Z, Chen J. Mutation screening of the USH2A gene reveals two novel pathogenic variants in Chinese patients causing simplex usher syndrome 2. BMC Ophthalmol 2020; 20:70. [PMID: 32093671 PMCID: PMC7038606 DOI: 10.1186/s12886-020-01342-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 02/13/2020] [Indexed: 12/19/2022] Open
Abstract
Background Usher syndrome (USH) is the most prevalent cause of the human genetic deafness and blindness. USH type II (USH2) is the most common form of USH, and USH2A is the major pathogenic gene for USH2. For expanding the spectrum of USH2A mutations and further revealing the role of USH2A in USH2, we performed the USH2A gene variant screening in Chinese patients with USH2. Methods Genomic DNA was extracted from peripheral blood of unrelated Chinese USH2 patients, we designed specific primers for amplifying the coding region (exons 2–72) of the USH2A gene. Sanger sequencing was used to study alleles. Silico prediction tools were used to predict the pathogenicity of the variants identified in these patients. Results Five heterozygous pathogenic variants were detected in four patients. Two patients were found to have two-mutations and two patients only have one. Two novel variants c.4217C > A (p.Ser1406X) and c.11780A > G (p.Asp3927Gly)) were predicted deleterious by computer prediction algorithms. In addition, three reported mutations (c.8559-2A > G, c.8232G > C and c.11389 + 3A > T) were also found in this study. Conclusions We identified five heterozygous pathogenic variants in the USH2A gene in Chinese patients diagnosed with Usher syndrome type 2, two of which were not reported. It expands the spectrum of USH2A variants in USH.
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Affiliation(s)
- Chenhao He
- Birth defect group, Translation Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai, 200081, China.,Department of Medical Genetics, Tongji University School of Medicine, Shanghai, 200092, China.,Department of Pediatrics of Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200092, China
| | - Xinyu Liu
- Birth defect group, Translation Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai, 200081, China.,Department of Medical Genetics, Tongji University School of Medicine, Shanghai, 200092, China.,Department of Pediatrics of Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200092, China
| | - Zilin Zhong
- Birth defect group, Translation Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai, 200081, China.,Department of Medical Genetics, Tongji University School of Medicine, Shanghai, 200092, China.,Department of Pediatrics of Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200092, China.,Department of Ophthalmology of Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, 200092, China
| | - Jianjun Chen
- Birth defect group, Translation Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai, 200081, China. .,Department of Medical Genetics, Tongji University School of Medicine, Shanghai, 200092, China. .,Department of Pediatrics of Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200092, China. .,Department of Ophthalmology of Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, 200092, China. .,Birth defect group, Medical wing building, Tongji University School of Medicine, 1239 SipingRoad Yangpu District, Shanghai, 200092, China.
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Knockout of ush2a gene in zebrafish causes hearing impairment and late onset rod-cone dystrophy. Hum Genet 2018; 137:779-794. [PMID: 30242501 DOI: 10.1007/s00439-018-1936-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 09/16/2018] [Indexed: 10/28/2022]
Abstract
Most cases of Usher syndrome type II (USH2) are due to mutations in the USH2A gene. There are no effective treatments or ideal animal models for this disease, and the pathological mechanisms of USH2 caused by USH2A mutations are still unknown. Here, we constructed a ush2a knockout (ush2a-/-) zebrafish model using TALEN technology to investigate the molecular pathology of USH2. An early onset auditory disorder and abnormal morphology of inner ear stereocilia were identified in the ush2a-/- zebrafish. Consequently, the disruption of Ush2a in zebrafish led to a hearing impairment, like that in mammals. Electroretinography (ERG) test indicated that deletion of Ush2a affected visual function at an early stage, and histological analysis revealed that the photoreceptors progressively degenerated. Rod degeneration occurred prior to cone degeneration in ush2a-/- zebrafish, which is consistent with the classical description of the progression of retinitis pigmentosa (RP). Destruction of the outer segments (OSs) of rods led to the down-regulation of phototransduction cascade proteins at late stage. The expression of Ush1b and Ush1c was up-regulated when Ush2a was null. We also found that disruption of fibronectin assembly at the retinal basement membrane weakened cell adhesion in ush2a-/- mutants. In summary, for the first time, we generated a ush2a knockout zebrafish line with auditory disorder and retinal degeneration which mimicked the symptoms of patients, and revealed that disruption of fibronectin assembly may be one of the factors underlying RP. This model may help us to better understand the pathogenic mechanism and find treatment for USH2 in the future.
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Jiang L, Liang X, Li Y, Wang J, Zaneveld JE, Wang H, Xu S, Wang K, Wang B, Chen R, Sui R. Comprehensive molecular diagnosis of 67 Chinese Usher syndrome probands: high rate of ethnicity specific mutations in Chinese USH patients. Orphanet J Rare Dis 2015; 10:110. [PMID: 26338283 PMCID: PMC4559966 DOI: 10.1186/s13023-015-0329-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 08/26/2015] [Indexed: 12/13/2022] Open
Abstract
Background Usher syndrome (USH) is the most common disease causing combined deafness and blindness. It is predominantly an autosomal recessive genetic disorder with occasionally digenic cases. Molecular diagnosis of USH patients is important for disease management. Few studies have tried to find the genetic cause of USH in Chinese patients. This study was designed to determine the mutation spectrum of Chinese USH patients. Methods We applied next generation sequencing to characterize the mutation spectrum in 67 independent Chinese families with at least one member diagnosed with USH. Blood was collected at Peking Union Medical College Hospital. This cohort is one of the largest USH cohorts reported. We utilized customized panel and whole exome sequencing, variant analysis, Sanger validation and segregation tests to find disease causing mutations in these families. Results We identified biallelic disease causing mutations in known USH genes in 70 % (49) of our patients. As has been previously reported, MYO7A is the most frequently mutated gene in our USH type I patients while USH2A is the most mutated gene in our USH type II patients. In addition, we identify mutations in CLRN1, DFNB31, GPR98 and PCDH15 for the first time in Chinese USH patients. Together, mutations in CLRN1, DNFB31, GPR98 and PCDH15 account for 11.4 % of disease in our cohort. Interestingly, although the spectrum of disease genes is quite similar between our Chinese patient cohort and other patient cohorts from different (and primarily Caucasian) ethnic backgrounds, the mutations themselves are dramatically different. In particular, 76 % (52/68) of alleles found in this study have never been previously reported. Interestingly, we observed a strong enrichment for severe protein truncating mutations expected to have severe functional consequence on the protein in USH II patients compared to the reported mutation spectrum in RP patients, who often carry partial protein truncating mutations. Conclusions Our study provides the first comprehensive genetic characterization of a large collection of Chinese USH patients. Up to 90 % of USH patients have disease caused by mutations in known USH disease genes. By combining NGS-based molecular diagnosis and patient clinical information, a more accurate diagnosis, prognosis and personalized treatment of USH patients can be achieved. Electronic supplementary material The online version of this article (doi:10.1186/s13023-015-0329-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lichun Jiang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Xiaofang Liang
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, 1 Shuai Fu Yuan, Beijing, 10073, China.
| | - Yumei Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Jing Wang
- Department of Medical Genetics, School of Basic Medical Sciences, Capital Medical University, Beijing, China.
| | - Jacques Eric Zaneveld
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Hui Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Shan Xu
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Keqing Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Binbin Wang
- Graduate School of Peking Union Medical College, Beijing, China. .,National Research Institute for Family Planning, Beijing, China.
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA. .,Structural and Computational Biology and Molecular Biophysics Program, Baylor College of Medicine, Houston, TX, 77030, USA. .,Program in Developmental Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Ruifang Sui
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, 1 Shuai Fu Yuan, Beijing, 10073, China.
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Kersten FF, van Wijk E, Hetterschijt L, Bauβ K, Peters TA, Aslanyan MG, van der Zwaag B, Wolfrum U, Keunen JE, Roepman R, Kremer H. The mitotic spindle protein SPAG5/Astrin connects to the Usher protein network postmitotically. Cilia 2012; 1:2. [PMID: 23351521 PMCID: PMC3541543 DOI: 10.1186/2046-2530-1-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 04/25/2012] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED BACKGROUND Mutations in the gene for Usher syndrome 2A (USH2A) are causative for non-syndromic retinitis pigmentosa and Usher syndrome, a condition that is the most common cause of combined deaf-blindness. To gain insight into the molecular pathology underlying USH2A-associated retinal degeneration, we aimed to identify interacting proteins of USH2A isoform B (USH2AisoB) in the retina. RESULTS We identified the centrosomal and microtubule-associated protein sperm-associated antigen (SPAG)5 in the retina. SPAG5 was also found to interact with another previously described USH2AisoB interaction partner: the centrosomal ninein-like protein NINLisoB. Using In situ hybridization, we found that Spag5 was widely expressed during murine embryonic development, with prominent signals in the eye, cochlea, brain, kidney and liver. SPAG5 expression in adult human tissues was detected by quantitative PCR, which identified expression in the retina, brain, intestine, kidney and testis. In the retina, Spag5, Ush2aisoB and NinlisoB were present at several subcellular structures of photoreceptor cells, and colocalized at the basal bodies. CONCLUSIONS Based on these results and on the suggested roles for USH proteins in vesicle transport and providing structural support to both the inner ear and the retina, we hypothesize that SPAG5, USH2AisoB and NINLisoB may function together in microtubule-based cytoplasmic trafficking of proteins that are essential for cilium formation, maintenance and/or function.
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Affiliation(s)
- Ferry Fj Kersten
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
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Xu W, Dai H, Lu T, Zhang X, Dong B, Li Y. Seven novel mutations in the long isoform of the USH2A gene in Chinese families with nonsyndromic retinitis pigmentosa and Usher syndrome Type II. Mol Vis 2011; 17:1537-52. [PMID: 21686329 PMCID: PMC3115748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 06/03/2011] [Indexed: 10/26/2022] Open
Abstract
PURPOSE To describe the clinical and genetic findings in one Chinese family with autosomal recessive retinitis pigmentosa (arRP) and in three unrelated Chinese families with Usher syndrome type II (USH2). METHODS One family (FR1) with arRP and three unrelated families (F6, F7, and F8) with Usher syndrome (USH), including eight affected members and seven unaffected family individuals were examined clinically. The study included 100 normal Chinese individuals as normal controls. After obtaining informed consent, peripheral blood samples from all participants were collected and genomic DNA was extracted. Genotyping and haplotyping analyses were performed on the known genetic loci for arRP with a panel of polymorphic markers in family FR1. In all four families, the coding region (exons 2-72), including the intron-exon boundary of the USH2A (Usher syndrome type -2A protein) gene, was screened by PCR and direct DNA sequencing. Whenever substitutions were identified in a patient, a restriction fragment length polymorphism (RFLP) analysis, single strand conformation polymorphism (SSCP) analysis, or high resolution melt curve analysis (HRM) was performed on all available family members and on the 100 normal controls. RESULTS The affected individuals presented with typical fundus features of retinitis pigmentosa (RP), including narrowing of the vessels, bone-spicule pigmentation, and waxy optic discs. The electroretinogram (ERG) wave amplitudes of the available probands were undetectable. Audiometric tests in the affected individuals in family FR1 were normal, while indicating moderate to severe sensorineural hearing impairment in the affected individuals in families F6, F7, and F8. Vestibular function was normal in all patients from all four families. The disease-causing gene in family FR1 was mapped to the USH2A locus on chromosome 1q41. Seven novel mutations (two missenses, one 7-bp deletion, two small deletions, and two nonsenses) were detected in the four families after sequencing analysis of USH2A. CONCLUSIONS The results further support that mutations of USH2A are also responsible for non-syndromic RP. The mutation spectrum among Chinese patients might differ from that among European Caucasians.
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