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Zi F, Li Z, Cheng W, Huang X, Sheng X, Rong W. Novel mutations of the X-linked genes associated with early-onset high myopia in five Chinese families. BMC Med Genomics 2023; 16:223. [PMID: 37749571 PMCID: PMC10521526 DOI: 10.1186/s12920-023-01665-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 09/18/2023] [Indexed: 09/27/2023] Open
Abstract
PURPOSE To report novel pathogenic variants of X-linked genes in five Chinese families with early-onset high myopia (eoHM) by using whole-exome sequencing and analyzing the phenotypic features. METHODS 5 probands with X-linked recessive related eoHM were collected in Ningxia Eye Hospital from January 2021 to June 2022. The probands and their family members received comprehensive ophthalmic examinations,and DNA was abstracted from patients and family members. Whole-exome sequencing was performed on probands to screen the causative variants, and all suspected pathogenic variants were determined by Sanger sequencing and co-segregation analysis was performed on available family members. The pathogenicity of novel variants was predicted using silico analysis and evaluated according to ACMG guidelines. RT-qPCR was used to detect differences in the relative mRNAs expression of candidate gene in mRNAs available with the proband and family members in the pedigree 2. The relationship between genetic variants and clinical features was analyzed. RESULTS All probands were male, and all pedigrees conformed to an X-linked recessive inheritance pattern. They were diagnosed with high myopia at their first visits between 4 and 7 years old. Spherical equivalent ranged between - 6.00D and - 11.00D.The five novel hemizygous variants were found in the probands, containing frameshift deletion variant c.797_801del (p.Val266Alafs*75) of OPN1LW gene in the pedigree 1, nonsense variant c.513G > A (p.Trp171Ter)of RP2 gene in the pedigree 2, missense variant c.98G > T (p.Cys33Phe) of GPR143 gene in the pedigree 3, frameshift deletion variant c.1876_1877del (p.Met626Valfs*22) of FRMD7 gene in the pedigree 4 and inframe deletion variant c.670_ 675del (p.Glu192_ Glu193del) of HMGB3 gene in the pedigree 5. All variants were classified as pathogenic or likely pathogenic by the interpretation principles of HGMD sequence variants and ACMG guidelines. In family 2, RT-qPCR showed that the mRNA expression of RP2 gene was lower in the proband than in other normal family members, indicating that such variant caused an effect on gene function at the mRNA expression level. Further clinical examination showed that pedigrees 1, 2, 3, and 4 were diagnosed as X-linked recessive hereditary eye disease with early-onset high myopia, including quiescent cone dysfunction, retinitis pigmentosa, ocular albinism, and idiopathic congenital nystagmus respectively. The pedigree 5 had eoHM in the right eye and ptosis in both eyes. CONCLUSION In this paper,we are the first to report five novel hemizygous variants in OPN1LW, RP2, GPR143, FRMD7, HMGB3 genes are associated with eoHM. Our study extends the genotypic spectrums for eoHM and better assists ophthalmologists in assessing, diagnosing, and conducting genetic screening for eoHM.
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Affiliation(s)
- Feiyin Zi
- Clinical Medical College, Ningxia Medical University, Yinchuan, 750001, China
| | - Zhen Li
- Department of Ophthalmology, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, Third Clinical Medical College of Ningxia Medical University, 936 Huanghe East Road, Jinfeng District, Yinchuan, 750001, China
| | - Wanyu Cheng
- Clinical Medical College, Ningxia Medical University, Yinchuan, 750001, China
| | - Xiaoyu Huang
- Clinical Medical College, Ningxia Medical University, Yinchuan, 750001, China
| | - Xunlun Sheng
- Gansu Aier Ophthalmiology and Optometry Hospital, 1228 Guazhou Road, Qilihe District, Lanzhou, 730050, China.
| | - Weining Rong
- Department of Ophthalmology, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, Third Clinical Medical College of Ningxia Medical University, 936 Huanghe East Road, Jinfeng District, Yinchuan, 750001, China.
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Lee HW, Lee EK. Asymmetric presentation with a novel RP2 gene mutation in X-Linked retinitis pigmentosa: a case report. BMC Ophthalmol 2023; 23:221. [PMID: 37198560 DOI: 10.1186/s12886-023-02968-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 05/09/2023] [Indexed: 05/19/2023] Open
Abstract
BACKGROUND We present the detailed multimodal imaging analysis in a case of X-linked retinitis pigmentosa (XLRP) exhibiting a markedly asymmetric presentation with a novel RP2 mutation. CASE PRESENTATION A 25-year-old woman complained of decreased vision in the right eye as well as night blindness. Her visual acuity was 20/100 (OD) and 20/20 (OS). Fundus examination revealed bone spicule pigmentation with tessellated changes in the fundus within the posterior pole. Optical coherence tomography (OCT) showed generalized disruption of foveal microstructures in the OD. No abnormal findings were identified, but localized ellipsoid zone band losses were observed on OCT in the OS. Fundus autofluorescence revealed multiple patchy hypo-autofluorescent lesions in the OD and a tapetal-like radial reflex against a dark background in the OS. Fluorescein angiography and OCT angiography revealed diffuse mottled hyperfluorescence with reduced retinal vessel density in the OD and no evidence of vascular compromise in the OS. Goldmann perimetry demonstrated a constricted visual field, and electrophysiological assessment revealed an extinguished rod response and a severely impaired cone response in the OD. Molecular genetic tests via next-generation sequencing revealed the pathogenic variant to be a heterozygous frameshift mutation in RP2 (RP2, p.Glu269Glyfs*7), resulting in premature termination of the protein. CONCLUSIONS Random X-inactivation may be attributed to interocular differences in the severity of XLRP in female carriers. A novel frameshift mutation in the RP2 gene and a comprehensive phenotypic evaluation in the current study may broaden the spectrum of the disease in XLRP carriers.
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Affiliation(s)
- Hyun Woo Lee
- Pre-medical Program, Seoul National University College of Medicine, Seoul, Korea
| | - Eun Kyoung Lee
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Hospital, #101, Daehak-ro, Jongno-gu, Seoul, Republic of Korea.
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Mansouri V. X-Linked Retinitis Pigmentosa Gene Therapy: Preclinical Aspects. Ophthalmol Ther 2022; 12:7-34. [PMID: 36346573 PMCID: PMC9641696 DOI: 10.1007/s40123-022-00602-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 10/17/2022] [Indexed: 11/11/2022] Open
Abstract
The most common inherited eye disease is retinitis pigmentosa (RP). X-linked RP (XLRP) is one of the most severe types of RP, with a considerable disease burden. Patients with XLRP experience a decrease in their vision and become blind in their 4th decade of life, causing much morbidity after starting a rather normal life. Treatment of XLRP remains challenging, and current treatments are not effective enough in restoring vision. Gene therapy of XLRP, capable of restoring the functional RPGR gene, showed promising results in preclinical studies and clinical trials; however, to date, no approved product has entered the market. The development of a gene therapy product needs through preliminary assessment of the drug in animal models before administration to humans. In this article, we reviewed the genetic pathology of XLRP, along with the preclinical aspects of the XLRP gene therapy, animal models, associated assessments, and future challenges and directions.
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Affiliation(s)
- Vahid Mansouri
- Gene Therapy Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
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Fujinami K, Liu X, Ueno S, Mizota A, Shinoda K, Kuniyoshi K, Fujinami-Yokokawa Y, Yang L, Arno G, Pontikos N, Kameya S, Kominami T, Terasaki H, Sakuramoto H, Nakamura N, Kurihara T, Tsubota K, Miyake Y, Yoshiake K, Iwata T, Tsunoda K. RP2-associated retinal disorder in a Japanese cohort: Report of novel variants and a literature review, identifying a genotype-phenotype association. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:675-693. [PMID: 32875684 DOI: 10.1002/ajmg.c.31830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/28/2020] [Accepted: 07/28/2020] [Indexed: 01/10/2023]
Abstract
The retinitis pigmentosa 2 (RP2) gene is one of the causative genes for X-linked inherited retinal disorder. We characterized the clinical/genetic features of four patients with RP2-associated retinal disorder (RP2-RD) from four Japanese families in a nationwide cohort. A systematic review of RP2-RD in the Japanese population was also performed. All four patients were clinically diagnosed with retinitis pigmentosa (RP). The mean age at examination was 36.5 (10-47) years, and the mean visual acuity in the right/left eye was 1.40 (0.52-2.0)/1.10 (0.52-1.7) in the logarithm of the minimum angle of resolution unit, respectively. Three patients showed extensive retinal atrophy with macular involvement, and one had central retinal atrophy. Four RP2 variants were identified, including two novel missense (p.Ser6Phe, p.Leu189Pro) and two previously reported truncating variants (p.Arg120Ter, p.Glu269CysfsTer3). The phenotypes of two patients with truncating variants were more severe than the phenotypes of two patients with missense variants. A systematic review revealed additional 11 variants, including three missense and eight deleterious (null) variants, and a statistically significant association between phenotype severity and genotype severity was revealed. The clinical and genetic spectrum of RP2-RD was illustrated in the Japanese population, identifying the characteristic features of a severe form of RP with early macular involvement.
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Affiliation(s)
- Kaoru Fujinami
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Xiao Liu
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.,Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Atsushi Mizota
- Department of Ophthalmology, Teikyo University, Tokyo, Japan
| | - Kei Shinoda
- Department of Ophthalmology, Teikyo University, Tokyo, Japan.,Department of Ophthalmology, Saitama Medical University, Moroyama Campus, Saitama, Japan
| | - Kazuki Kuniyoshi
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
| | - Yu Fujinami-Yokokawa
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Department of Health Policy and Management, Keio University School of Medicine, Tokyo, Japan.,Division of Public Health, Yokokawa Clinic, Suita, Japan
| | - Lizhu Yang
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Gavin Arno
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK.,North East Thames Regional Genetics Service, UCL Great Ormond Street Institute of Child Health, NHS Foundation Trust, London, UK
| | - Nikolas Pontikos
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
| | - Shuhei Kameya
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Japan
| | - Taro Kominami
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroyuki Sakuramoto
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
| | - Natsuko Nakamura
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Teikyo University, Tokyo, Japan.,Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Toshihide Kurihara
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Kazuo Tsubota
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Yozo Miyake
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Aichi Medical University, Nagakute, Japan.,Next vision, Kobe Eye Center, Kobe, Japan
| | - Kazutoshi Yoshiake
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Kazushige Tsunoda
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
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X-linked Retinitis Pigmentosa in Japan: Clinical and Genetic Findings in Male Patients and Female Carriers. Int J Mol Sci 2019; 20:ijms20061518. [PMID: 30917587 PMCID: PMC6470860 DOI: 10.3390/ijms20061518] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 03/23/2019] [Accepted: 03/25/2019] [Indexed: 12/18/2022] Open
Abstract
X-linked retinitis pigmentosa (XLRP) is a type of severe retinal dystrophy, and female carriers of XLRP demonstrate markedly variable clinical severity. In this study, we aimed to elucidate the clinical findings of male patients with and female carriers of XLRP in a Japanese cohort and demonstrate the genetic contribution. Twelve unrelated families (13 male patients, 15 female carriers) harboring pathogenic mutations in RPGR or RP2 were included, and comprehensive ophthalmic examinations were performed. To identify potential pathogenic mutations, targeted next-generation sequencing was employed. Consequently, we identified 11 pathogenic mutations, of which five were novel. Six and five mutations were detected in RPGR and RP2, respectively. Only one mutation was detected in ORF15. Affected male patients with RP2 mutations tended to have lower visual function than those with RPGR mutations. Female carriers demonstrated varying visual acuities and visual fields. Among the female carriers, 92% had electroretinographical abnormalities and 63% had a radial autofluorescent pattern, and the carriers who had higher myopia showed worse visual acuity and more severe retinal degeneration. Our results expand the knowledge of the clinical phenotypes of male patients with and female carriers of XLRP and suggest the possibility that RP2 mutations are relatively highly prevalent in Japan.
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Fu YC, Chen N, Qiu ZL, Liu L, Shen J. Compound pathogenic mutation in the USH2A gene in Chinese RP families detected by whole‑exome sequencing. Mol Med Rep 2018; 18:5016-5022. [PMID: 30280194 PMCID: PMC6236299 DOI: 10.3892/mmr.2018.9530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 09/04/2018] [Indexed: 12/19/2022] Open
Abstract
Retinitis pigmentosa (RP) is a common form of inherited retinal degeneration that causes progressive loss of vision or adult blindness, characterized by the impairment of rod and cone photoreceptors. At present, mutations in >60 pathogenic genes have been confirmed to cause RP. The predominant modes of inheritance are autosomal dominant, autosomal recessive and X‑linked. In addition, other modes of inheritance, including digenic or mitochondrial inheritance, have been reported. In previous decades, with the development of sequencing techniques, significant advances in identifying novel RP pathogenic genes and screening mutations have been made. In the present study, whole‑exome sequencing was performed on samples from two Chinese pedigrees diagnosed with RP. A compound heterozygous mutation in the gene usherin 2A (USH2A; c.6,485+5G>A/c.11,156G>A) and a heterozygous X‑linked mutation in the gene retinitis pigmentosa 2 (RP2) ARL3 GTPase‑activating protein (RP2; c.358C>T) were identified by Sanger sequencing and co‑segregation analysis, of which the pathogenic mutation (c.6,485+5G>A) in USH2A has not been previously reported among Chinese patients. The findings of the present study may expand on current knowledge of RP among the Chinese population, providing essential assistance in the molecular diagnosis and screening of RP, and promoting further investigation of the pathogenesis of RP.
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Affiliation(s)
- Yue-Chuan Fu
- Department of Ophthalmology, The Shanghai Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200120, P.R. China
| | - Na Chen
- Department of Ophthalmology, The Shanghai Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200120, P.R. China
| | - Zi-Long Qiu
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, P.R. China
| | - Lin Liu
- Department of Ophthalmology, The Shanghai Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200120, P.R. China
| | - Jie Shen
- Department of Ophthalmology, The Shanghai Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200120, P.R. China
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Di Iorio V, Karali M, Brunetti-Pierri R, Filippelli M, Di Fruscio G, Pizzo M, Mutarelli M, Nigro V, Testa F, Banfi S, Simonelli F. Clinical and Genetic Evaluation of a Cohort of Pediatric Patients with Severe Inherited Retinal Dystrophies. Genes (Basel) 2017; 8:genes8100280. [PMID: 29053603 PMCID: PMC5664130 DOI: 10.3390/genes8100280] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/02/2017] [Accepted: 10/13/2017] [Indexed: 12/30/2022] Open
Abstract
We performed a clinical and genetic characterization of a pediatric cohort of patients with inherited retinal dystrophy (IRD) to identify the most suitable cases for gene therapy. The cohort comprised 43 patients, aged between 2 and 18 years, with severe isolated IRD at the time of presentation. The ophthalmological characterization also included assessment of the photoreceptor layer integrity in the macular region (ellipsoid zone (EZ) band). In parallel, we carried out a targeted, next-generation sequencing (NGS)-based analysis using a panel that covers over 150 genes with either an established or a candidate role in IRD pathogenesis. Based on the ophthalmological assessment, the cohort was composed of 24 Leber congenital amaurosis, 14 early onset retinitis pigmentosa, and 5 achromatopsia patients. We identified causative mutations in 58.1% of the cases. We also found novel genotype-phenotype correlations in patients harboring mutations in the CEP290 and CNGB3 genes. The EZ band was detectable in 40% of the analyzed cases, also in patients with genotypes usually associated with severe clinical manifestations. This study provides the first detailed clinical-genetic assessment of severe IRDs with infantile onset and lays the foundation of a standardized protocol for the selection of patients that are more likely to benefit from gene replacement therapeutic approaches.
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Affiliation(s)
- Valentina Di Iorio
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania Luigi Vanvitelli, via Pansini 5, Naples 80131, Italy.
| | - Marianthi Karali
- Medical Genetics, Department of Biochemistry, Biophysics and General Pathology, Università degli Studi della Campania Luigi Vanvitelli, via Luigi De Crecchio 7, Naples 80138, Italy.
- Telethon Institute of Genetics and Medicine, via Campi Flegrei 34, Pozzuoli 80078, Italy.
| | - Raffaella Brunetti-Pierri
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania Luigi Vanvitelli, via Pansini 5, Naples 80131, Italy.
| | - Mariaelena Filippelli
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania Luigi Vanvitelli, via Pansini 5, Naples 80131, Italy.
| | - Giuseppina Di Fruscio
- Medical Genetics, Department of Biochemistry, Biophysics and General Pathology, Università degli Studi della Campania Luigi Vanvitelli, via Luigi De Crecchio 7, Naples 80138, Italy.
| | - Mariateresa Pizzo
- Telethon Institute of Genetics and Medicine, via Campi Flegrei 34, Pozzuoli 80078, Italy.
| | - Margherita Mutarelli
- Telethon Institute of Genetics and Medicine, via Campi Flegrei 34, Pozzuoli 80078, Italy.
| | - Vincenzo Nigro
- Medical Genetics, Department of Biochemistry, Biophysics and General Pathology, Università degli Studi della Campania Luigi Vanvitelli, via Luigi De Crecchio 7, Naples 80138, Italy.
- Telethon Institute of Genetics and Medicine, via Campi Flegrei 34, Pozzuoli 80078, Italy.
| | - Francesco Testa
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania Luigi Vanvitelli, via Pansini 5, Naples 80131, Italy.
| | - Sandro Banfi
- Medical Genetics, Department of Biochemistry, Biophysics and General Pathology, Università degli Studi della Campania Luigi Vanvitelli, via Luigi De Crecchio 7, Naples 80138, Italy.
- Telethon Institute of Genetics and Medicine, via Campi Flegrei 34, Pozzuoli 80078, Italy.
| | - Francesca Simonelli
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania Luigi Vanvitelli, via Pansini 5, Naples 80131, Italy.
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Bujakowska KM, Liu Q, Pierce EA. Photoreceptor Cilia and Retinal Ciliopathies. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a028274. [PMID: 28289063 DOI: 10.1101/cshperspect.a028274] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Photoreceptors are sensory neurons designed to convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer segments (OS) of rod and cone photoreceptors. OS are specialized sensory cilia, with analogous structures to those present in other nonmotile cilia. Deficient morphogenesis and/or dysfunction of photoreceptor sensory cilia (PSC) caused by mutations in a variety of photoreceptor-specific and common cilia genes can lead to inherited retinal degenerations (IRDs). IRDs can manifest as isolated retinal diseases or syndromic diseases. In this review, we describe the structure and composition of PSC and different forms of ciliopathies with retinal involvement. We review the genetics of the IRDs, which are monogenic disorders but genetically diverse with regard to causality.
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Affiliation(s)
- Kinga M Bujakowska
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Qin Liu
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Eric A Pierce
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
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9
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Genetic characterization and disease mechanism of retinitis pigmentosa; current scenario. 3 Biotech 2017; 7:251. [PMID: 28721681 DOI: 10.1007/s13205-017-0878-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 07/10/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa is a group of genetically transmitted disorders affecting 1 in 3000-8000 individual people worldwide ultimately affecting the quality of life. Retinitis pigmentosa is characterized as a heterogeneous genetic disorder which leads by progressive devolution of the retina leading to a progressive visual loss. It can occur in syndromic (with Usher syndrome and Bardet-Biedl syndrome) as well as non-syndromic nature. The mode of inheritance can be X-linked, autosomal dominant or autosomal recessive manner. To date 58 genes have been reported to associate with retinitis pigmentosa most of them are either expressed in photoreceptors or the retinal pigment epithelium. This review focuses on the disease mechanisms and genetics of retinitis pigmentosa. As retinitis pigmentosa is tremendously heterogeneous disorder expressing a multiplicity of mutations; different variations in the same gene might induce different disorders. In recent years, latest technologies including whole-exome sequencing contributing effectively to uncover the hidden genesis of retinitis pigmentosa by reporting new genetic mutations. In future, these advancements will help in better understanding the genotype-phenotype correlations of disease and likely to develop new therapies.
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10
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Liu F, Qin Y, Yu S, Soares DC, Yang L, Weng J, Li C, Gao M, Lu Z, Hu X, Liu X, Jiang T, Liu JY, Shu X, Tang Z, Liu M. Pathogenic mutations in retinitis pigmentosa 2 predominantly result in loss of RP2 protein stability in humans and zebrafish. J Biol Chem 2017; 292:6225-6239. [PMID: 28209709 PMCID: PMC5391753 DOI: 10.1074/jbc.m116.760314] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 02/14/2017] [Indexed: 12/20/2022] Open
Abstract
Mutations in retinitis pigmentosa 2 (RP2) account for 10-20% of X-linked retinitis pigmentosa (RP) cases. The encoded RP2 protein is implicated in ciliary trafficking of myristoylated and prenylated proteins in photoreceptor cells. To date >70 mutations in RP2 have been identified. How these mutations disrupt the function of RP2 is not fully understood. Here we report a novel in-frame 12-bp deletion (c.357_368del, p.Pro120_Gly123del) in zebrafish rp2 The mutant zebrafish shows reduced rod phototransduction proteins and progressive retinal degeneration. Interestingly, the protein level of mutant Rp2 is almost undetectable, whereas its mRNA level is near normal, indicating a possible post-translational effect of the mutation. Consistent with this hypothesis, the equivalent 12-bp deletion in human RP2 markedly impairs RP2 protein stability and reduces its protein level. Furthermore, we found that a majority of the RP2 pathogenic mutations (including missense, single-residue deletion, and C-terminal truncation mutations) severely destabilize the RP2 protein. The destabilized RP2 mutant proteins are degraded via the proteasome pathway, resulting in dramatically decreased protein levels. The remaining non-destabilizing mutations T87I, R118H/R118G/R118L/R118C, E138G, and R211H/R211L are suggested to impair the interaction between RP2 and its protein partners (such as ARL3) or with as yet unknown partners. By utilizing a combination of in silico, in vitro, and in vivo approaches, our work comprehensively indicates that loss of RP2 protein structural stability is the predominating pathogenic consequence for most RP2 mutations. Our study also reveals a role of the C-terminal domain of RP2 in maintaining the overall protein stability.
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Affiliation(s)
- Fei Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Yayun Qin
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Shanshan Yu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Dinesh C Soares
- MRC Human Genetics Unit/Centre for Genomic and Experimental Medicine, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom, and
| | - Lifang Yang
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Jun Weng
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Chang Li
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Meng Gao
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Zhaojing Lu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xuebin Hu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xiliang Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Tao Jiang
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Jing Yu Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xinhua Shu
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, United Kingdom
| | - Zhaohui Tang
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Mugen Liu
- From the Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China,
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Broadgate S, Yu J, Downes SM, Halford S. Unravelling the genetics of inherited retinal dystrophies: Past, present and future. Prog Retin Eye Res 2017; 59:53-96. [PMID: 28363849 DOI: 10.1016/j.preteyeres.2017.03.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023]
Abstract
The identification of the genes underlying monogenic diseases has been of interest to clinicians and scientists for many years. Using inherited retinal dystrophies as an example of monogenic disease we describe the history of molecular genetic techniques that have been pivotal in the discovery of disease causing genes. The methods that were developed in the 1970's and 80's are still in use today but have been refined and improved. These techniques enabled the concept of the Human Genome Project to be envisaged and ultimately realised. When the successful conclusion of the project was announced in 2003 many new tools and, as importantly, many collaborations had been developed that facilitated a rapid identification of disease genes. In the post-human genome project era advances in computing power and the clever use of the properties of DNA replication has allowed the development of next-generation sequencing technologies. These methods have revolutionised the identification of disease genes because for the first time there is no need to define the position of the gene in the genome. The use of next generation sequencing in a diagnostic setting has allowed many more patients with an inherited retinal dystrophy to obtain a molecular diagnosis for their disease. The identification of novel genes that have a role in the development or maintenance of retinal function is opening up avenues of research which will lead to the development of new pharmacological and gene therapy approaches. Neither of which can be used unless the defective gene and protein is known. The continued development of sequencing technologies also holds great promise for the advent of truly personalised medicine.
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Affiliation(s)
- Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Jing Yu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Susan M Downes
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, Oxford, OX3 9DU, UK
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK.
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Analysis of RP2 and RPGR Mutations in Five X-Linked Chinese Families with Retinitis Pigmentosa. Sci Rep 2017; 7:44465. [PMID: 28294154 PMCID: PMC5353642 DOI: 10.1038/srep44465] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/08/2017] [Indexed: 11/08/2022] Open
Abstract
Mutations in RP2 and RPGR genes are responsible for the X-linked retinitis pigmentosa (XLRP). In this study, we analyzed the RP2 and RPGR gene mutations in five Han Chinese families with XLRP. An approximately 17Kb large deletion including the exon 4 and exon 5 of RP2 gene was found in an XLRP family. In addition, four frameshift mutations including three novel mutations of c.1059 + 1 G > T, c.2002dupC and c.2236_2237del CT, as well as a previously reported mutation of c.2899delG were detected in the RPGR gene in the other four families. Our study further expands the mutation spectrum of RP2 and RPGR, and will be helpful for further study molecular pathogenesis of XLRP.
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Whole exome sequencing using Ion Proton system enables reliable genetic diagnosis of inherited retinal dystrophies. Sci Rep 2017; 7:42078. [PMID: 28181551 PMCID: PMC5299602 DOI: 10.1038/srep42078] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 01/05/2017] [Indexed: 01/17/2023] Open
Abstract
Inherited retinal dystrophies (IRD) comprise a wide group of clinically and genetically complex diseases that progressively affect the retina. Over recent years, the development of next-generation sequencing (NGS) methods has transformed our ability to diagnose heterogeneous diseases. In this work, we have evaluated the implementation of whole exome sequencing (WES) for the molecular diagnosis of IRD. Using Ion ProtonTM system, we simultaneously analyzed 212 genes that are responsible for more than 25 syndromic and non-syndromic IRD. This approach was used to evaluate 59 unrelated families, with the pathogenic variant(s) successfully identified in 71.18% of cases. Interestingly, the mutation detection rate varied substantially depending on the IRD subtype. Overall, we found 63 different mutations (21 novel) in 29 distinct genes, and performed in vivo functional studies to determine the deleterious impact of variants identified in MERTK, CDH23, and RPGRIP1. In addition, we provide evidences that support CDHR1 as a gene responsible for autosomal recessive retinitis pigmentosa with early macular affectation, and present data regarding the disease mechanism of this gene. Altogether, these results demonstrate that targeted WES of all IRD genes is a reliable, hypothesis-free approach, and a cost- and time-effective strategy for the routine genetic diagnosis of retinal dystrophies.
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Ullah I, Kabir F, Iqbal M, Gottsch CBS, Naeem MA, Assir MZ, Khan SN, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Pathogenic mutations in TULP1 responsible for retinitis pigmentosa identified in consanguineous familial cases. Mol Vis 2016; 22:797-815. [PMID: 27440997 PMCID: PMC4947966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 07/14/2016] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To identify pathogenic mutations responsible for autosomal recessive retinitis pigmentosa (arRP) in consanguineous familial cases. METHODS Seven large familial cases with multiple individuals diagnosed with retinitis pigmentosa were included in the study. Affected individuals in these families underwent ophthalmic examinations to document the symptoms and confirm the initial diagnosis. Blood samples were collected from all participating members, and genomic DNA was extracted. An exclusion analysis with microsatellite markers spanning the TULP1 locus on chromosome 6p was performed, and two-point logarithm of odds (LOD) scores were calculated. All coding exons along with the exon-intron boundaries of TULP1 were sequenced bidirectionally. We constructed a single nucleotide polymorphism (SNP) haplotype for the four familial cases harboring the K489R allele and estimated the likelihood of a founder effect. RESULTS The ophthalmic examinations of the affected individuals in these familial cases were suggestive of RP. Exclusion analyses confirmed linkage to chromosome 6p harboring TULP1 with positive two-point LOD scores. Subsequent Sanger sequencing identified the single base pair substitution in exon14, c.1466A>G (p.K489R), in four families. Additionally, we identified a two-base deletion in exon 4, c.286_287delGA (p.E96Gfs77*); a homozygous splice site variant in intron 14, c.1495+4A>C; and a novel missense variation in exon 15, c.1561C>T (p.P521S). All mutations segregated with the disease phenotype in the respective families and were absent in ethnically matched control chromosomes. Haplotype analysis suggested (p<10(-6)) that affected individuals inherited the causal mutation from a common ancestor. CONCLUSIONS Pathogenic mutations in TULP1 are responsible for the RP phenotype in seven familial cases with a common ancestral mutation responsible for the disease phenotype in four of the seven families.
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Affiliation(s)
- Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Muhammad Iqbal
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Zaman Assir
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California, San Diego, CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
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Kabir F, Ullah I, Ali S, Gottsch AD, Naeem MA, Assir MZ, Khan SN, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Loss of function mutations in RP1 are responsible for retinitis pigmentosa in consanguineous familial cases. Mol Vis 2016; 22:610-25. [PMID: 27307693 PMCID: PMC4901054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 06/08/2016] [Indexed: 10/31/2022] Open
Abstract
PURPOSE This study was undertaken to identify causal mutations responsible for autosomal recessive retinitis pigmentosa (arRP) in consanguineous families. METHODS Large consanguineous families were ascertained from the Punjab province of Pakistan. An ophthalmic examination consisting of a fundus evaluation and electroretinography (ERG) was completed, and small aliquots of blood were collected from all participating individuals. Genomic DNA was extracted from white blood cells, and a genome-wide linkage or a locus-specific exclusion analysis was completed with polymorphic short tandem repeats (STRs). Two-point logarithm of odds (LOD) scores were calculated, and all coding exons and exon-intron boundaries of RP1 were sequenced to identify the causal mutation. RESULTS The ophthalmic examination showed that affected individuals in all families manifest cardinal symptoms of RP. Genome-wide scans localized the disease phenotype to chromosome 8q, a region harboring RP1, a gene previously implicated in the pathogenesis of RP. Sanger sequencing identified a homozygous single base deletion in exon 4: c.3697delT (p.S1233Pfs22*), a single base substitution in intron 3: c.787+1G>A (p.I263Nfs8*), a 2 bp duplication in exon 2: c.551_552dupTA (p.Q185Yfs4*) and an 11,117 bp deletion that removes all three coding exons of RP1. These variations segregated with the disease phenotype within the respective families and were not present in ethnically matched control samples. CONCLUSIONS These results strongly suggest that these mutations in RP1 are responsible for the retinal phenotype in affected individuals of all four consanguineous families.
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Affiliation(s)
- Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shahbaz Ali
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Zaman Assir
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California, San Diego, CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
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Strom SP, Clark MJ, Martinez A, Garcia S, Abelazeem AA, Matynia A, Parikh S, Sullivan LS, Bowne SJ, Daiger SP, Gorin MB. De Novo Occurrence of a Variant in ARL3 and Apparent Autosomal Dominant Transmission of Retinitis Pigmentosa. PLoS One 2016; 11:e0150944. [PMID: 26964041 PMCID: PMC4786330 DOI: 10.1371/journal.pone.0150944] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 02/22/2016] [Indexed: 11/19/2022] Open
Abstract
Background Retinitis pigmentosa is a phenotype with diverse genetic causes. Due to this genetic heterogeneity, genome-wide identification and analysis of protein-altering DNA variants by exome sequencing is a powerful tool for novel variant and disease gene discovery. In this study, exome sequencing analysis was used to search for potentially causal DNA variants in a two-generation pedigree with apparent dominant retinitis pigmentosa. Methods Variant identification and analysis of three affected members (mother and two affected offspring) was performed via exome sequencing. Parental samples of the index case were used to establish inheritance. Follow-up testing of 94 additional retinitis pigmentosa pedigrees was performed via retrospective analysis or Sanger sequencing. Results and Conclusions A total of 136 high quality coding variants in 123 genes were identified which are consistent with autosomal dominant disease. Of these, one of the strongest genetic and functional candidates is a c.269A>G (p.Tyr90Cys) variant in ARL3. Follow-up testing established that this variant occurred de novo in the index case. No additional putative causal variants in ARL3 were identified in the follow-up cohort, suggesting that if ARL3 variants can cause adRP it is an extremely rare phenomenon.
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Affiliation(s)
- Samuel P. Strom
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
| | - Michael J. Clark
- Personalis Inc., Menlo Park, California, United States of America
| | - Ariadna Martinez
- Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Sarah Garcia
- Personalis Inc., Menlo Park, California, United States of America
| | | | - Anna Matynia
- Jules Stein Eye Institute and Department of Ophthalmology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sachin Parikh
- Jules Stein Eye Institute and Department of Ophthalmology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Lori S. Sullivan
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Sara J. Bowne
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Stephen P. Daiger
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Michael B. Gorin
- Jules Stein Eye Institute and Department of Ophthalmology, University of California Los Angeles, Los Angeles, California, United States of America
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Schwarz N, Carr AJ, Lane A, Moeller F, Chen LL, Aguilà M, Nommiste B, Muthiah MN, Kanuga N, Wolfrum U, Nagel-Wolfrum K, da Cruz L, Coffey PJ, Cheetham ME, Hardcastle AJ. Translational read-through of the RP2 Arg120stop mutation in patient iPSC-derived retinal pigment epithelium cells. Hum Mol Genet 2015; 24:972-86. [PMID: 25292197 PMCID: PMC4986549 DOI: 10.1093/hmg/ddu509] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/29/2014] [Indexed: 01/08/2023] Open
Abstract
Mutations in the RP2 gene lead to a severe form of X-linked retinitis pigmentosa. RP2 patients frequently present with nonsense mutations and no treatments are currently available to restore RP2 function. In this study, we reprogrammed fibroblasts from an RP2 patient carrying the nonsense mutation c.519C>T (p.R120X) into induced pluripotent stem cells (iPSC), and differentiated these cells into retinal pigment epithelial cells (RPE) to study the mechanisms of disease and test potential therapies. RP2 protein was undetectable in the RP2 R120X patient cells, suggesting a disease mechanism caused by complete lack of RP2 protein. The RP2 patient fibroblasts and iPSC-derived RPE cells showed phenotypic defects in IFT20 localization, Golgi cohesion and Gβ1 trafficking. These phenotypes were corrected by over-expressing GFP-tagged RP2. Using the translational read-through inducing drugs (TRIDs) G418 and PTC124 (Ataluren), we were able to restore up to 20% of endogenous, full-length RP2 protein in R120X cells. This level of restored RP2 was sufficient to reverse the cellular phenotypic defects observed in both the R120X patient fibroblasts and iPSC-RPE cells. This is the first proof-of-concept study to demonstrate successful read-through and restoration of RP2 function for the R120X nonsense mutation. The ability of the restored RP2 protein level to reverse the observed cellular phenotypes in cells lacking RP2 indicates that translational read-through could be clinically beneficial for patients.
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Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Amanda-Jayne Carr
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Amelia Lane
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Fabian Moeller
- Johannes Gutenberg-University Muellerweg 6, 55099 Mainz, Germany and
| | - Li Li Chen
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Mònica Aguilà
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Britta Nommiste
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Manickam N Muthiah
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK, Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK
| | - Naheed Kanuga
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Uwe Wolfrum
- Johannes Gutenberg-University Muellerweg 6, 55099 Mainz, Germany and
| | | | - Lyndon da Cruz
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK, Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK
| | - Peter J Coffey
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
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Petrs-Silva H, Linden R. Advances in gene therapy technologies to treat retinitis pigmentosa. Clin Ophthalmol 2013; 8:127-36. [PMID: 24391438 PMCID: PMC3878960 DOI: 10.2147/opth.s38041] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Retinitis pigmentosa (RP) is a class of diseases that leads to progressive degeneration of the retina. Experimental approaches to gene therapy for the treatment of inherited retinal dystrophies have advanced in recent years, inclusive of the safe delivery of genes to the human retina. This review is focused on the development of gene therapy for RP using recombinant adenoassociated viral vectors, which show a positive safety record and have so far been successful in several clinical trials for congenital retinal disease. Gene therapy for RP is under development in a variety of animal models, and the results raise expectations of future clinical application. Nonetheless, the translation of such strategies to the bedside requires further understanding of the mutations and mechanisms that cause visual defects, as well as thorough examination of potential adverse effects.
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Affiliation(s)
- Hilda Petrs-Silva
- Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rafael Linden
- Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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Abstract
PURPOSE OF REVIEW To describe the entity of Lyonization in ocular eye diseases, along with its clinical and counseling implications. RECENT FINDINGS Several X-linked ocular diseases such as choroideremia, X-linked retinitis pigmentosa, and X-linked ocular albinism may have signs of Lyonization on ocular examination and diagnostic testing. These findings may aid in the proper diagnosis of ocular disease in both female carriers and their affected male relatives. SUMMARY Manifestations of Lyonization in the eye may help in the diagnosis of X-linked ocular diseases which may lead to accurate diagnosis, appropriate molecular genetic testing and genetic counseling.
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Estrada-Cuzcano A, Roepman R, Cremers FPM, den Hollander AI, Mans DA. Non-syndromic retinal ciliopathies: translating gene discovery into therapy. Hum Mol Genet 2012; 21:R111-24. [PMID: 22843501 DOI: 10.1093/hmg/dds298] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Homozygosity mapping and exome sequencing have accelerated the discovery of gene mutations and modifier alleles implicated in inherited retinal degeneration in humans. To date, 158 genes have been found to be mutated in individuals with retinal dystrophies. Approximately one-third of the gene defects underlying retinal degeneration affect the structure and/or function of the 'connecting cilium' in photoreceptors. This structure corresponds to the transition zone of a prototypic cilium, a region with increasing relevance for ciliary homeostasis. The connecting cilium connects the inner and outer segments of the photoreceptor, mediating bi-directional transport of phototransducing proteins required for vision. In fact, the outer segment, connecting cilium and associated basal body, forms a highly specialized sensory cilium, fully dedicated to photoreception and subsequent signal transduction to the brain. At least 21 genes that encode ciliary proteins are implicated in non-syndromic retinal dystrophies such as cone dystrophy, cone-rod dystrophy, Leber congenital amaurosis (LCA), macular degeneration or retinitis pigmentosa (RP). The generation and characterization of vertebrate retinal ciliopathy animal models have revealed insights into the molecular disease mechanism which are indispensable for the development and evaluation of therapeutic strategies. Gene augmentation therapy has proven to be safe and successful in restoring long-term sight in mice, dogs and humans suffering from LCA or RP. Here, we present a comprehensive overview of the genes, mutations and modifier alleles involved in non-syndromic retinal ciliopathies, review the progress in dissecting the associated retinal disease mechanisms and evaluate gene augmentation approaches to antagonize retinal degeneration in these ciliopathies.
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Structural and functional characteristics in carriers of X-linked retinitis pigmentosa with a tapetal-like reflex. Retina 2011; 30:1726-33. [PMID: 20829740 DOI: 10.1097/iae.0b013e3181dde629] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE The purpose of this study was to identify the functional and structural characteristics in three female obligate carriers of X-linked retinitis pigmentosa from the same family by using spectral domain optical coherence tomography, fundus autofluorescence, and microperimetry. METHODS Three female obligate carriers with a tapetal-like reflex, 21, 49, and 57 years of age, from a single family of X-linked retinitis pigmentosa that was seen in the ophthalmology department at the University of Illinois at Chicago, were enrolled in the study. All carriers underwent a complete ophthalmic examination. Spectral domain optical coherence tomography measurements, a macular microperimetry examination, and fundus autofluorescence testing were performed. RESULTS The spectral domain optical coherence tomography examination in all three carriers showed a normal retinal microstructure and thickness. Microperimeter testing showed subnormal retinal sensitivity in the areas of the tapetal-like reflex. Fundus autofluorescence examination showed the presence of speckled areas of enhanced autofluorescence. CONCLUSION Our study demonstrates that the carriers of X-linked retinitis pigmentosa with a tapetal-like reflex can show an enhanced reflectance on infrared images, abnormal autofluorescence properties, elevated retinal thresholds, and a normal retinal morphology within the posterior pole on spectral domain optical coherence tomography testing.
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Hurd T, Zhou W, Jenkins P, Liu CJ, Swaroop A, Khanna H, Martens J, Hildebrandt F, Margolis B. The retinitis pigmentosa protein RP2 interacts with polycystin 2 and regulates cilia-mediated vertebrate development. Hum Mol Genet 2010; 19:4330-44. [PMID: 20729296 DOI: 10.1093/hmg/ddq355] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Ciliopathies represent a growing group of human genetic diseases whose etiology lies in defects in ciliogenesis or ciliary function. Given the established entity of renal-retinal ciliopathies, we have been examining the role of cilia-localized proteins mutated in retinitis pigmentosa (RP) in regulating renal ciliogenesis or cilia-dependent signaling cascades. Specifically, this study examines the role of the RP2 gene product with an emphasis on renal and vertebrate development. We demonstrate that in renal epithelia, RP2 localizes to the primary cilium through dual acylation of the amino-terminus. We also show that RP2 forms a calcium-sensitive complex with the autosomal dominant polycystic kidney disease protein polycystin 2. Ablation of RP2 by shRNA promotes swelling of the cilia tip that may be a result of aberrant trafficking of polycystin 2 and other ciliary proteins. Morpholino-mediated repression of RP2 expression in zebrafish results in multiple developmental defects that have been previously associated with ciliary dysfunction, such as hydrocephalus, kidney cysts and situs inversus. Finally, we demonstrate that, in addition to our observed physical interaction between RP2 and polycystin 2, dual morpholino-mediated knockdown of polycystin 2 and RP2 results in enhanced situs inversus, indicating that these two genes also regulate a common developmental process. This work suggests that RP2 may be an important regulator of ciliary function through its association with polycystin 2 and provides evidence of a further link between retinal and renal cilia function.
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Affiliation(s)
- Toby Hurd
- Department of Pediatrics and Communicable Diseases, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA.
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Jayasundera T, Branham KEH, Othman M, Rhoades WR, Karoukis AJ, Khanna H, Swaroop A, Heckenlively JR. RP2 phenotype and pathogenetic correlations in X-linked retinitis pigmentosa. ACTA ACUST UNITED AC 2010; 128:915-23. [PMID: 20625056 DOI: 10.1001/archophthalmol.2010.122] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVES To assess the phenotype of patients with X-linked retinitis pigmentosa (XLRP) with RP2 mutations and to correlate the findings with their genotype. METHODS Six hundred eleven patients with RP were screened for RP2 mutations. From this screen, 18 patients with RP2 mutations were evaluated clinically with standardized electroretinography, Goldmann visual fields, and ocular examinations. In addition, 7 well-documented cases from the literature were used to augment genotype-phenotype correlations. RESULTS Of 11 boys younger than 12 years, 10 (91%) had macular involvement and 9 (82%) had best-corrected visual acuity worse than 20/50. Two boys from different families (aged 8 and 12 years) displayed a choroideremia-like fundus, and 9 boys (82%) were myopic (mean error, -7.97 diopters [D]). Of 10 patients with electroretinography data, 9 demonstrated severe rod-cone dysfunction. All 3 female carriers had macular atrophy in 1 or both eyes and were myopic (mean, -6.23 D). All 9 nonsense and frameshift and 5 of 7 missense mutations (71%) resulted in severe clinical presentations. CONCLUSIONS Screening of the RP2 gene should be prioritized in patients younger than 16 years characterized by X-linked inheritance, decreased best-corrected visual acuity (eg, >20/40), high myopia, and early-onset macular atrophy. Patients exhibiting a choroideremia-like fundus without choroideremia gene mutations should also be screened for RP2 mutations. CLINICAL RELEVANCE An identifiable phenotype for RP2-XLRP aids in clinical diagnosis and targeted genetic screening.
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Affiliation(s)
- Thiran Jayasundera
- Department of Ophthalmologyand Visual Sciences, Kellogg Eye Center, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105, USA
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Murga-Zamalloa CA, Swaroop A, Khanna H. RPGR-containing protein complexes in syndromic and non-syndromic retinal degeneration due to ciliary dysfunction. J Genet 2010; 88:399-407. [PMID: 20090203 DOI: 10.1007/s12041-009-0061-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dysfunction of primary cilia due to mutations in cilia-centrosomal proteins is associated with pleiotropic disorders. The primary (or sensory) cilium of photoreceptors mediates polarized trafficking of proteins for efficient phototransduction. Retinitis pigmentosa GTPase regulator (RPGR) is a cilia-centrosomal protein mutated in >70% of X-linked RP cases and 10%-20% of simplex RP males. Accumulating evidence indicates that RPGR may facilitate the orchestration of multiple ciliary protein complexes. Disruption of these complexes due to mutations in component proteins is an underlying cause of associated photoreceptor degeneration. Here, we highlight the recent developments in understanding the mechanism of cilia-dependent photoreceptor degeneration due to mutations in RPGR and PGR-interacting proteins in severe genetic diseases, including retinitis pigmentosa, Leber congenital amaurosis (LCA), Joubert syndrome, and Senior-Loken syndrome, and explore the physiological relevance of photoreceptor ciliary protein complexes.
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Affiliation(s)
- Carlos A Murga-Zamalloa
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA
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Murga-Zamalloa C, Swaroop A, Khanna H. Multiprotein complexes of Retinitis Pigmentosa GTPase regulator (RPGR), a ciliary protein mutated in X-linked Retinitis Pigmentosa (XLRP). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 664:105-14. [PMID: 20238008 DOI: 10.1007/978-1-4419-1399-9_13] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mutations in Retinitis Pigmentosa GTPase Regulator (RPGR) are a frequent cause of X-linked Retinitis Pigmentosa (XLRP). The RPGR gene undergoes extensive alternative splicing and encodes for distinct protein isoforms in the retina. Extensive studies using isoform-specific antibodies and mouse mutants have revealed that RPGR predominantly localizes to the transition zone to primary cilia and associates with selected ciliary and microtubule-associated assemblies in photoreceptors. In this chapter, we have summarized recent advances on understanding the role of RPGR in photoreceptor protein trafficking. We also provide new evidence that suggests the existence of discrete RPGR multiprotein complexes in photoreceptors. Piecing together the RPGR-interactome in different subcellular compartments should provide critical insights into the role of alternative RPGR isoforms in associated orphan and syndromic retinal degenerative diseases.
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Affiliation(s)
- Carlos Murga-Zamalloa
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, Ann Arbor, MI 48105, USA
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Sherwin JC, Hewitt AW, Ruddle JB, Mackey DA. Genetic isolates in ophthalmic diseases. Ophthalmic Genet 2008; 29:149-61. [PMID: 19005985 DOI: 10.1080/13816810802334341] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In recent years, noteworthy gains have been made in unravelling the genetic contribution to some complex ocular diseases, principally age-related macular degeneration. Yet, a relatively poor understanding of the genetic aetiology for many other heritable blinding diseases, such as glaucoma, keratoconus and myopia, remains. Genetic isolates, populations with varying degrees of geographical or cultural seclusion, provide an effective means for investigating the molecular mechanisms involved in human diseases. This is particularly true for rare diseases in which founded alleles can be rapidly driven to a high frequency due to restriction of gene flow in the population. Recent success in complex gene mapping has resulted from the widened linkage disequilibrium (LD) in the genome of genetically isolated populations. An improved understanding of the predisposing genetic risk factors allows for enhanced screening modalities and paves the foundations for the translation of genomic technology into the clinic. This review focuses on the role population isolates have had in the investigation of genes underlying complex eye diseases and discusses their likely usefulness given the expansion of large-scale case-control association studies.
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Affiliation(s)
- Justin C Sherwin
- Department of Ophthalmology, Centre for Eye Research Australia, University of Melbourne, elbourne, Australia
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Pelletier V, Jambou M, Delphin N, Zinovieva E, Stum M, Gigarel N, Dollfus H, Hamel C, Toutain A, Dufier JL, Roche O, Munnich A, Bonnefont JP, Kaplan J, Rozet JM. Comprehensive survey of mutations in RP2 and RPGR in patients affected with distinct retinal dystrophies: genotype-phenotype correlations and impact on genetic counseling. Hum Mutat 2007; 28:81-91. [PMID: 16969763 DOI: 10.1002/humu.20417] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
X-linked forms of retinitis pigmentosa (RP) (XLRP) account for 10 to 20% of families with RP and are mainly accounted for by mutations in the RP2 or RP GTPase regulator (RPGR) genes. We report the screening of these genes in a cohort of 127 French family comprising: 1) 93 familial cases of RP suggesting X-linked inheritance, including 48 out of 93 families with expression in females but no male to male transmission; 2) seven male sibships of RP; 3) 25 sporadic male cases of RP; and 4) two cone dystrophies (COD). A total of 5 out of the 93 RP families excluded linkage to the RP2 and RP3 loci and were removed form the cohort. A total of 14 RP2 mutations, 12 of which are novel, were identified in 14 out of 88 familial cases of RP and 1 out of 25 sporadic male case (4%). In 13 out of 14 of the familial cases, no expression of the disease was noted in females, while in 1 out of 14 families one woman developed RP in the third decade. A total of 42 RPGR mutations, 26 of which were novel, were identified in 80 families, including: 69 out of 88 familial cases (78.4%); 2 out of 7 male sibship (28.6%); 8 out of 25 sporadic male cases (32.0%); and 1 out of 2 COD. No expression of the disease was noted in females in 41 out of 69 familial cases (59.4%), while at least one severely affected woman was recognized in 28 out of 69 families (40.6%). The frequency of RP2 and RPGR mutations in familial cases of RP suggestive of X-linked transmission are in accordance to that reported elsewhere (RP2: 15.9% vs. 6-20%; RPGR: 78.4% vs. 55-90%). Interestingly, about 30% of male sporadic cases and 30% of male sibships of RP carried RP2 or RPGR mutations, confirming the pertinence of the genetic screening of XLRP genes in male patients affected with RP commencing in the first decade and leading to profound visual impairment before the age of 30 years.
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Affiliation(s)
- Valérie Pelletier
- Unité de Recherches Génétique et Epigénétique des Maladies Métaboliques, Neurosensorielles et du Développement, Institut Nationale de la Santé et de la Recherche Médicale (INSERM) U781, Hôpital Necker-Enfants Malades, Paris, France
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Melamud A, Shen GQ, Chung D, Xi Q, Simpson E, Li L, Peachey NS, Zegarra H, Hagstrom SA, Wang QK, Traboulsi EI. Mapping a new genetic locus for X linked retinitis pigmentosa to Xq28. J Med Genet 2006; 43:e27. [PMID: 16740911 PMCID: PMC2593026 DOI: 10.1136/jmg.2005.031518] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We have defined a new genetic locus for an X linked form of retinitis pigmentosa (RP) on chromosome Xq28. We examined 15 members of a family in which RP appeared to be transmitted in an X linked manner. Ocular examinations were performed, and fundus photographs and electroretinograms were obtained for selected patients. Blood samples were obtained from all patients and an additional seven family members who were not given examinations. Visual acuity in four affected individuals ranged from 20/40 to 20/80+. Patients described the onset of night blindness and colour vision defects in the second decade of life, with the earliest at 13 years of age. Examined affected individuals had constricted visual fields and retinal findings compatible with RP. Based on full field electroretinography, cone function was more severely reduced than rod function. Female carriers had no ocular signs or symptoms and slightly reduced cone electroretinographic responses. Affected and non-affected family members were genotyped for 20 polymorphic markers on the X-chromosome spaced at 10 cM intervals. Genotyping data were analysed using GeneMapper software. Genotyping and linkage analyses identified significant linkage to markers DXS8061, DXS1073, and DXS1108 with two point LOD scores of 2.06, 2.17, and 2.20, respectively. Haplotype analysis revealed segregation of the disease phenotype with markers at Xq28.
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Kühnel K, Veltel S, Schlichting I, Wittinghofer A. Crystal Structure of the Human Retinitis Pigmentosa 2 Protein and Its Interaction with Arl3. Structure 2006; 14:367-78. [PMID: 16472755 DOI: 10.1016/j.str.2005.11.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 10/24/2005] [Accepted: 11/01/2005] [Indexed: 11/29/2022]
Abstract
The crystal structure of human retinitis pigmentosa 2 protein (RP2) was solved to 2.1 angstroms resolution. It consists of an N-terminal beta helix and a C-terminal ferredoxin-like alpha/beta domain. RP2 is functionally and structurally related to the tubulin-specific chaperone cofactor C. Seven of nine known RP2 missense mutations identified in patients are located in the beta helix domain, and most of them cluster to the hydrophobic core and are likely to destabilize the protein. Two residues, Glu138 and the catalytically important Arg118, are solvent-exposed and form a salt bridge, indicating that Glu138 might be critical for positioning Arg118 for catalysis. RP2 is a specific effector protein of Arl3. The N-terminal 34 residues and beta helix domain of RP2 are required for this interaction. The abilitities of RP2 to bind Arl3 and cause retinitis pigmentosa seem to be correlated, since both the R118H and E138G mutants show a drastically reduced affinity to Arl3.
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Affiliation(s)
- Karin Kühnel
- Max-Planck-Institut für Molekulare Physiologie, Abteilung Strukturelle Biologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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Weleber RG, Gregory-Evans K. Retinitis Pigmentosa and Allied Disorders. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50023-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Moore A, Escudier E, Roger G, Tamalet A, Pelosse B, Marlin S, Clément A, Geremek M, Delaisi B, Bridoux AM, Coste A, Witt M, Duriez B, Amselem S. RPGR is mutated in patients with a complex X linked phenotype combining primary ciliary dyskinesia and retinitis pigmentosa. J Med Genet 2005; 43:326-33. [PMID: 16055928 PMCID: PMC2563225 DOI: 10.1136/jmg.2005.034868] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Primary ciliary dyskinesia (PCD) is a rare disease classically transmitted as an autosomal recessive trait and characterised by recurrent airway infections due to abnormal ciliary structure and function. To date, only two autosomal genes, DNAI1 and DNAH5 encoding axonemal dynein chains, have been shown to cause PCD with defective outer dynein arms. Here, we investigated one non-consanguineous family in which a woman with retinitis pigmentosa (RP) gave birth to two boys with a complex phenotype combining PCD, discovered in early childhood and characterised by partial dynein arm defects, and RP that occurred secondarily. The family history prompted us to search for an X linked gene that could account for both conditions. RESULTS We found perfect segregation of the disease phenotype with RP3 associated markers (Xp21.1). Analysis of the retinitis pigmentosa GTPase regulator gene (RPGR) located at this locus revealed a mutation (631_IVS6+9del) in the two boys and their mother. As shown by study of RPGR transcripts expressed in nasal epithelial cells, this intragenic deletion, which leads to activation of a cryptic donor splice site, predicts a severely truncated protein. CONCLUSION These data provide the first clear demonstration of X linked transmission of PCD. This unusual mode of inheritance of PCD in patients with particular phenotypic features (that is, partial dynein arm defects and association with RP), which should modify the current management of families affected by PCD or RP, unveils the importance of RPGR in the proper development of both respiratory ciliary structures and connecting cilia of photoreceptors.
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Affiliation(s)
- A Moore
- Institut National de la Santé et de la Recherche Médicale U. 654, Hôpital Henri-Mondor, Créteil, France
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Dodatko T, Fedorov AA, Grynberg M, Patskovsky Y, Rozwarski DA, Jaroszewski L, Aronoff-Spencer E, Kondraskina E, Irving T, Godzik A, Almo SC. Crystal structure of the actin binding domain of the cyclase-associated protein. Biochemistry 2004; 43:10628-41. [PMID: 15311924 DOI: 10.1021/bi049071r] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclase-associated protein (CAP or Srv2p) is a modular actin monomer binding protein that directly regulates filament dynamics and has been implicated in a number of complex developmental and morphological processes, including mRNA localization and the establishment of cell polarity. The crystal structure of the C-terminal dimerization and actin monomer binding domain (C-CAP) reveals a highly unusual dimer, composed of monomers possessing six coils of right-handed beta-helix flanked by antiparallel beta-strands. Domain swapping, involving the last two strands of each monomer, results in the formation of an extended dimer with an extensive interface. This structural and biochemical characterization provides new insights into the organization and potential mechanistic properties of the multiprotein assemblies that integrate dynamic actin processes into the overall physiology of the cell. An unanticipated finding is that the unique tertiary structure of the C-CAP monomer provides a structural model for a wide range of molecules, including RP2 and cofactor C, proteins involved in X-linked retinitis pigmentosa and tubulin maturation, respectively, as well as several uncharacterized proteins that exhibit very diverse domain organizations. Thus, the unusual right-handed beta-helical fold present in C-CAP appears to support a wide range of biological functions.
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Affiliation(s)
- Tetyana Dodatko
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Dandekar SS, Ebenezer ND, Grayson C, Chapple JP, Egan CA, Holder GE, Jenkins SA, Fitzke FW, Cheetham ME, Webster AR, Hardcastle AJ. An atypical phenotype of macular and peripapillary retinal atrophy caused by a mutation in the RP2 gene. Br J Ophthalmol 2004; 88:528-32. [PMID: 15031171 PMCID: PMC1772091 DOI: 10.1136/bjo.2003.027979] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To determine the molecular basis and describe the phenotype of an atypical retinal dystrophy in a family presenting with bilateral, progressive central visual loss. METHODS Family members were examined. Investigations included Goldman perimetry, electrophysiology, and autofluorescence imaging. Candidate gene screening was performed using SSCP and sequence analysis. The proband's lymphoblastoid cells were examined for protein expression. RESULTS Fundal examination of the proband, his mother, and brother revealed peripapillary and macular atrophy. Autosomal dominant retinal dystrophy was suspected, but less severe disease in the mother led to screening for mutations in X linked genes. A 4 bp microdeletion in exon 3 of the RP2 gene, segregating with disease, was identified. No RP2 protein expression was detected. CONCLUSION The distinct phenotype in this family, caused by this frameshifting mutation in RP2, broadens the phenotypic spectrum of X linked retinitis pigmentosa. The absence of RP2 protein suggests that loss of protein function and not novel gain of function could account for the atypical phenotype. A definitive diagnosis of X linked retinitis pigmentosa permits appropriate genetic counselling with important implications for other family members. Clinicians should have a low threshold for screening RP2 in families with retinal dystrophy, including posterior retinal disease, not immediately suggestive of X linked inheritance.
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Andréasson S, Breuer DK, Eksandh L, Ponjavic V, Frennesson C, Hiriyanna S, Filippova E, Yashar BM, Swaroop A. Clinical studies of X-linked retinitis pigmentosa in three Swedish families with newly identified mutations in the RP2 and RPGR-ORF15 genes. Ophthalmic Genet 2004; 24:215-23. [PMID: 14566651 DOI: 10.1076/opge.24.4.215.17228] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE To describe new disease-causing RP2 and RPGR-ORF15 mutations and their corresponding clinical phenotypes in Swedish families with X-linked retinitis pigmentosa (XLRP) and to establish genotype-phenotype correlations by studying the clinical spectrum of disease in families with a known molecular defect. METHODS Seventeen unrelated families with RP and an apparent X-linked pattern of disease inheritance were identified from the Swedish RP registry and screened for mutations in the RP2 and RPGR (for the RP3 disease) genes. These families had been previously screened for the RPGR exons 1-19, and disease-causing mutations were identified in four of them. In the remaining 13 families, we sequenced the RP2 gene and the newly discovered RPGR-ORF exon. Detailed clinical evaluations were then obtained from individuals in the three families with identified mutations. RESULTS Mutations in RP2 and RPGR-ORF15 were identified in three of the 13 families. Clinical evaluations of affected males and carrier females demonstrated varying degrees of retinal dysfunction and visual handicap, with early onset and severe disease in the families with mutations in the ORF15 exon of the RPGR gene. CONCLUSIONS A total of seven mutations in the RP2 and RPGR genes have been discovered so far in Swedish XLRP families. All affected individuals express a severe form of retinal degeneration with visual handicap early in life, although the degree of retinal dysfunction varies both in hemizygous male patients and in heterozygous carrier females. Retinal disease phenotypes in patients with mutations in the RPGR-ORF15 were more severe than in patients with mutations in RP2 or other regions of the RPGR.
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Affiliation(s)
- Sten Andréasson
- Department of Ophthalmology, University Hospital of Lund, Lund, Sweden.
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Vorster AA, Rebello MT, Coutts N, Ehrenreich L, Gama AD, Roberts LJ, Goliath R, Ramesar R, Greenberg LJ. Arg120stop nonsense mutation in the RP2 gene: mutational hotspot and germ line mosaicism? Clin Genet 2003; 65:7-10. [PMID: 15032968 DOI: 10.1111/j..2004.00163.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mutations in the RP2 gene account for up to 20% of X-linked recessive retinitis pigmentosa (RP). Arg120stop is to date the most frequently reported mutation found in RP2. Mutation screening was performed during the course of a large screening program of retinal degenerative disorders (RDDs) in South Africa using exon 1 and 2 of RP2 in 20 unrelated families with an X-linked mode of retinal degenerative inheritance. Direct sequencing analysis revealed a C-->T transition at position 358 in the proband in a family of German origin. Subsequent analysis revealed that this Arg120stop mutation cosegregated with the disease in an additional affected family member. The nonsense mutation, Arg120stop, could not however, be detected in the somatic cells of the obligate carrier female. This, the first report of a germ line mutation for a family with RP, has many implications for genetic counseling of retinal degeneration (RD). To avoid inaccurate risk assessment for RP due to epigenetic events, such as the rare occurrence of germ line mosaicism, genetic counseling in families with XLRP should always be guided by molecular testing.
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Affiliation(s)
- A A Vorster
- Division of Human Genetics, University of Cape Town, Medical School, Observatory, South Africa
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Sharon D, Sandberg MA, Rabe VW, Stillberger M, Dryja TP, Berson EL. RP2 and RPGR mutations and clinical correlations in patients with X-linked retinitis pigmentosa. Am J Hum Genet 2003; 73:1131-46. [PMID: 14564670 PMCID: PMC1180492 DOI: 10.1086/379379] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2003] [Accepted: 08/29/2003] [Indexed: 11/03/2022] Open
Abstract
We determined the mutation spectrum of the RP2 and RPGR genes in patients with X-linked retinitis pigmentosa (XLRP) and searched for correlations between categories of mutation and severity of disease. We screened 187 unrelated male patients for mutations, including 135 with a prior clinical diagnosis of XLRP, 11 with probable XLRP, 30 isolate cases suspected of having XLRP, and 11 with cone-rod degeneration. Mutation screening was performed by single-strand conformation analysis and by sequencing of all RP2 exons and RPGR exons 1-14, ORF15, and 15a. The refractive error, visual acuity, final dark-adapted threshold, visual field area, and 30-Hz cone electroretinogram (ERG) amplitude were measured in each patient. Among the 187 patients, we found 10 mutations in RP2, 2 of which are novel, and 80 mutations in RPGR, 41 of which are novel; 66% of the RPGR mutations were within ORF15. Among the 135 with a prior clinical diagnosis of XLRP, mutations in the RP2 and RPGR genes were found in 9 of 135 (6.7%) and 98 of 135 (72.6%), respectively, for a total of 79% of patients. Patients with RP2 mutations had, on average, lower visual acuity but similar visual field area, final dark-adapted threshold, and 30-Hz ERG amplitude compared with those with RPGR mutations. Among patients with RPGR mutations, those with ORF15 mutations had, on average, a significantly larger visual field area and a borderline larger ERG amplitude than did patients with RPGR mutations in exons 1-14. Among patients with ORF15 mutations, regression analyses showed that the final dark-adapted threshold became lower (i.e., closer to normal) and that the 30-Hz ERG amplitude increased as the length of the wild-type ORF15 amino acid sequence increased. Furthermore, as the length of the abnormal amino acid sequence following ORF15 frameshift mutations increased, the severity of disease increased.
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Affiliation(s)
- Dror Sharon
- Ocular Molecular Genetics Institute and the Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston
| | - Michael A. Sandberg
- Ocular Molecular Genetics Institute and the Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston
| | - Vivian W. Rabe
- Ocular Molecular Genetics Institute and the Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston
| | - Melissa Stillberger
- Ocular Molecular Genetics Institute and the Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston
| | - Thaddeus P. Dryja
- Ocular Molecular Genetics Institute and the Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston
| | - Eliot L. Berson
- Ocular Molecular Genetics Institute and the Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston
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Breuer DK, Yashar BM, Filippova E, Hiriyanna S, Lyons RH, Mears AJ, Asaye B, Acar C, Vervoort R, Wright AF, Musarella MA, Wheeler P, MacDonald I, Iannaccone A, Birch D, Hoffman DR, Fishman GA, Heckenlively JR, Jacobson SG, Sieving PA, Swaroop A. A comprehensive mutation analysis of RP2 and RPGR in a North American cohort of families with X-linked retinitis pigmentosa. Am J Hum Genet 2002; 70:1545-54. [PMID: 11992260 PMCID: PMC379141 DOI: 10.1086/340848] [Citation(s) in RCA: 181] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2002] [Accepted: 03/21/2002] [Indexed: 11/03/2022] Open
Abstract
X-linked retinitis pigmentosa (XLRP) is a clinically and genetically heterogeneous degenerative disease of the retina. At least five loci have been mapped for XLRP; of these, RP2 and RP3 account for 10%-20% and 70%-90% of genetically identifiable disease, respectively. However, mutations in the respective genes, RP2 and RPGR, were detected in only 10% and 20% of families with XLRP. Mutations in an alternatively spliced RPGR exon, ORF15, have recently been shown to account for 60% of XLRP in a European cohort of 47 families. We have performed, in a North American cohort of 234 families with RP, a comprehensive screen of the RP2 and RPGR (including ORF15) genes and their 5' upstream regions. Of these families, 91 (39%) show definitive X-linked inheritance, an additional 88 (38%) reveal a pattern consistent with X-linked disease, and the remaining 55 (23%) are simplex male patients with RP who had an early onset and/or severe disease. In agreement with the previous studies, we show that mutations in the RP2 gene and in the original 19 RPGR exons are detected in <10% and approximately 20% of XLRP probands, respectively. Our studies have revealed RPGR-ORF15 mutations in an additional 30% of 91 well-documented families with X-linked recessive inheritance and in 22% of the total 234 probands analyzed. We suggest that mutations in an as-yet-uncharacterized RPGR exon(s), intronic changes, or another gene in the region might be responsible for the disease in the remainder of this North American cohort. We also discuss the implications of our studies for genetic diagnosis, genotype-phenotype correlations, and gene-based therapy.
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Affiliation(s)
- Debra K. Breuer
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Beverly M. Yashar
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Elena Filippova
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Suja Hiriyanna
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Robert H. Lyons
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Alan J. Mears
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Bersabell Asaye
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Ceren Acar
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Raf Vervoort
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Alan F. Wright
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Maria A. Musarella
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Patricia Wheeler
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Ian MacDonald
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Alessandro Iannaccone
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - David Birch
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Dennis R. Hoffman
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Gerald A. Fishman
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - John R. Heckenlively
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Samuel G. Jacobson
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Paul A. Sieving
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
| | - Anand Swaroop
- Departments of Human Genetics, Ophthalmology and Visual Sciences, and Biological Chemistry and Sequencing Core Facility, University of Michigan, Ann Arbor; Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh; Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn; New England Medical Center, Boston; Department of Ophthalmology, University of Alberta, Edmonton, Alberta; Department of Ophthalmology, University of Tennessee Health Science Center, Memphis; Retina Foundation of the Southwest, Dallas; University of Illinois at Chicago, Chicago; Jules Stein Eye Institute, University of California at Los Angeles, Los Angeles; Scheie Eye Institute, University of Pennsylvania, Philadelphia; and National Eye Institute, Bethesda, MD
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38
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Ponting CP, Mott R, Bork P, Copley RR. Novel protein domains and repeats in Drosophila melanogaster: insights into structure, function, and evolution. Genome Res 2001; 11:1996-2008. [PMID: 11731489 DOI: 10.1101/gr.198701] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Sequence database searching methods such as BLAST, are invaluable for predicting molecular function on the basis of sequence similarities among single regions of proteins. Searches of whole databases however, are not optimized to detect multiple homologous regions within a single polypeptide. Here we have used the prospero algorithm to perform self-comparisons of all predicted Drosophila melanogaster gene products. Predicted repeats, and their homologs from all species, were analyzed further to detect hitherto unappreciated evolutionary relationships. Results included the identification of novel tandem repeats in the human X-linked retinitis pigmentosa type-2 gene product, repeated segments in cystinosin, associated with a defect in cystine transport, and 'nested' homologous domains in dysferlin, whose gene is mutated in limb girdle muscular dystrophy. Novel signaling domain families were found that may regulate the microtubule-based cytoskeleton and ubiquitin-mediated proteolysis, respectively. Two families of glycosyl hydrolases were shown to contain internal repetitions that hint at their evolution via a piecemeal, modular approach. In addition, three examples of fruit fly genes were detected with tandem exons that appear to have arisen via internal duplication. These findings demonstrate how completely sequenced genomes can be exploited to further understand the relationships between molecular structure, function, and evolution.
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MESH Headings
- Amino Acid Sequence/genetics
- Amino Acid Transport Systems, Neutral
- Animals
- Antigens, Differentiation, B-Lymphocyte/chemistry
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/physiology
- Aspartate-tRNA Ligase/chemistry
- Aspartate-tRNA Ligase/genetics
- Aspartate-tRNA Ligase/physiology
- Cystinosis/genetics
- Drosophila Proteins/chemistry
- Drosophila Proteins/genetics
- Drosophila Proteins/physiology
- Drosophila melanogaster/chemistry
- Drosophila melanogaster/enzymology
- Drosophila melanogaster/genetics
- Evolution, Molecular
- Exons/genetics
- Eye Proteins
- GTP-Binding Proteins
- Gene Duplication
- Glycoproteins
- Glycoside Hydrolases/chemistry
- Glycoside Hydrolases/genetics
- Glycoside Hydrolases/physiology
- Histocompatibility Antigens Class II/chemistry
- Histocompatibility Antigens Class II/genetics
- Histocompatibility Antigens Class II/physiology
- Humans
- Insect Proteins/chemistry
- Insect Proteins/genetics
- Insect Proteins/physiology
- Intracellular Signaling Peptides and Proteins
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/physiology
- Membrane Transport Proteins
- Molecular Sequence Data
- Muscular Dystrophies/genetics
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Proteins/chemistry
- Proteins/genetics
- Proteins/physiology
- Repetitive Sequences, Amino Acid
- Retinitis Pigmentosa/genetics
- Signal Transduction/genetics
- Species Specificity
- Tandem Repeat Sequences
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Affiliation(s)
- C P Ponting
- MRC Functional Genetics Unit, Department of Human Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK.
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Miano MG, Testa F, Filippini F, Trujillo M, Conte I, Lanzara C, Millán JM, De Bernardo C, Grammatico B, Mangino M, Torrente I, Carrozzo R, Simonelli F, Rinaldi E, Ventruto V, D'Urso M, Ayuso C, Ciccodicola A. Identification of novel RP2 mutations in a subset of X-linked retinitis pigmentosa families and prediction of new domains. Hum Mutat 2001; 18:109-19. [PMID: 11462235 DOI: 10.1002/humu.1160] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
X-linked Retinitis Pigmentosa (XLRP) shows a huge genetic heterogeneity with almost five distinct loci on the X chromosome. So far, only two XLRP genes have been identified, RPGR (or RP3) and RP2, being mutated in approximately 70% and 10% of the XLRP patients. Clinically there is no clearly significative difference between RP3 and RP2 phenotypes. In the attempt to assess the degree of involvement of the RP2 gene, we performed a complete mutation analysis in a cohort of patients and we identified five novel mutations in five different XLRP families. These mutations include three missense mutations, a splice site mutation, and a single base insertion, which, because of frameshift, anticipates a stop codon. Four mutations fall in RP2 exon 2 and one in exon 3. Evidence that such mutations are different from the 21 RP2 mutations described thus far suggests that a high mutation rate occurs at the RP2 locus, and that most mutations arise independently, without a founder effect. Our mutation analysis confirms the percentage of RP2 mutations detected so far in populations of different ethnic origin. In addition to novel mutations, we report here that a deeper sequence analysis of the RP2 product predicts, in addition to cofactor C homology domain, further putative functional domains, and that some novel mutations identify RP2 amino acid residues which are evolutionary conserved, hence possibly crucial to the RP2 function.
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Affiliation(s)
- M G Miano
- International Institute of Genetics and Biophysics, CNR, Naples, Italy
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40
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Mashima Y, Saga M, Akeo K, Oguchi Y. Phenotype associated with an R120X nonsense mutation in the RP2 gene in a Japanese family with X-linked retinitis pigmentosa. Ophthalmic Genet 2001; 22:43-7. [PMID: 11262649 DOI: 10.1076/opge.22.1.43.2238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We examined a Japanese family with X-linked retinitis pigmentosa (RP) associated with a nonsense mutation, R120X, in the RP2 gene. The 26-year-old proband presented at the age of seven years with a two-year history of night blindness. Visual disability worsened with increasing age. At age 24, visual acuity was 0.08 in both eyes. Testing for refractive error indicated mild myopia. Visual fields showed bilateral-constriction to 10 degrees. He had central macular areolar sclerosis in both eyes. Two maternal uncles had vision of light perception to hand movement in their early forties together with dense bilateral cataracts. The ocular phenotype of this family with R120X was considered severe; reported phenotypes associated with this mutation have not been uniform.
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Affiliation(s)
- Y Mashima
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
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41
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De Luca A, Torrente I, Mangino M, Danesi R, Dallapiccola B, Novelli G. Three novel mutations causing a truncated protein within the RP2 gene in Italian families with X-linked retinitis pigmentosa. Mutat Res 2001; 432:79-82. [PMID: 11465545 DOI: 10.1016/s1383-5726(00)00007-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
X-linked retinitis pigmentosa (XLRP) results from mutations in a number of loci, including RP2 at Xp11.3, and RP3 at Xp21.1. RP2 and RP3 genes have been identified by positional cloning. RP2 mutations are found in about 10% of XLRP patients. We performed a mutational screening of RP2 gene inpatients belonging to seven unrelated families in linkage with the RP2 locus. SSCP analysis detected three conformation variants, within exon 2 and 3. Direct sequencing of exon 2, disclosed a G-->A transition at nucleotide 449 (W150X), and a G-->T transversion in position 547 (E183X). Sequence analysis of exon 3 variant revealed an insertion (853/854insG), leading to a frameshift. In this patient, we detected an additional sequence alteration (A-->G at nucleotide 848, E283G). Each mutation was co-segregating with the disease in the affected family members available for the study. These mutations are expected to introduce a stop codon within the RP2 coding sequence probably resulting in a truncated or unstable protein.
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Affiliation(s)
- A De Luca
- Dipartimento di Biopatologia e Diagnostica per Immagini, Università di Roma Tor Vergata, Rome, Italy
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Mashima Y, Saga M, Hiida Y, Imamura Y, Kudoh J, Shimizu N. Novel mutation in RP2 gene in two brothers with X-linked retinitis pigmentosa and mtDNA mutation of leber hereditary optic neuropathy who showed marked differences in clinical severity. Am J Ophthalmol 2000; 130:357-9. [PMID: 11020419 DOI: 10.1016/s0002-9394(00)00553-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
PURPOSE To report the identification of a novel mutation of the RP2 gene in two Japanese brothers with X-linked retinitis pigmentosa of a differing clinical severity. The mother was a carrier of both retinitis pigmentosa and optic atrophy. METHODS The older brother had a severe form of retinitis pigmentosa associated with macular degeneration and total optic atrophy, whereas the younger brother presented typical X-linked retinitis pigmentosa. RESULTS Each patient exhibited a novel 2-bp insertion at codon 278 in exon 3 of the RP2 gene as well as a 11778 mutation in mitochondrial DNA. This suggests that the older brother may have developed Leber hereditary optic neuropathy as well as retinitis pigmentosa. CONCLUSION Molecular testing confirmed the clinical diagnosis in each case. However, such testing did not explain the differences in the severity of the ophthalmoscopic findings between the two brothers.
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Affiliation(s)
- Y Mashima
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
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Clarke G, Héon E, McInnes RR. Recent advances in the molecular basis of inherited photoreceptor degeneration. Clin Genet 2000; 57:313-29. [PMID: 10852366 DOI: 10.1034/j.1399-0004.2000.570501.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To date, 118 loci have been associated with photoreceptor degenerative disease. In this review, we will discuss recent advances in the identification of genes that cause progressive photoreceptor cell death when mutated. We will focus on 12 genes isolated within the last two years that have been shown to be photoreceptor-specific, or that have provided insight into photoreceptor biology and the mechanisms of photoreceptor cell death. To aid in understanding the biologic basis for these diseases, we also briefly review photoreceptor biology. Finally, we report on recent advances towards the treatment of these disorders.
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Affiliation(s)
- G Clarke
- Program in Developmental Biology and Genetics, The Research Institute, Hospital for Sick Children, Toronto, Ontario
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Kirschner R, Rosenberg T, Schultz-Heienbrok R, Lenzner S, Feil S, Roepman R, Cremers FP, Ropers HH, Berger W. RPGR transcription studies in mouse and human tissues reveal a retina-specific isoform that is disrupted in a patient with X-linked retinitis pigmentosa. Hum Mol Genet 1999; 8:1571-8. [PMID: 10401007 DOI: 10.1093/hmg/8.8.1571] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
X-linked retinitis pigmentosa (XLRP) is a genetically heterogeneous group of progressive retinal degenerations. The disease process is initiated by premature apoptosis of rod photoreceptor cells in the retina, which leads to reduced visual acuity and, eventually, complete blindness. Mutations in the retinitis pigmentosa GTPase regulator ( RPGR ), a ubiquitously expressed gene at the RP3 locus in Xp21.1, account for approximately 20% of all X-linked cases. We have analysed the expression of this gene by northern blot hybridization, cDNA library screening and RT-PCR in various organs from mouse and man. These studies revealed at least 12 alternatively spliced isoforms. Some of the transcripts are tissue specific and contain novel exons, which elongate or truncate the previously reported open reading frame of the mouse and human RPGR gene. One of the newly identified exons is expressed exclusively in the human retina and mouse eye and contains a premature stop codon. The deduced polypeptide lacks 169 amino acids from the C-terminus of the ubiquitously expressed variant, including an isoprenylation site. Moreover, this exon was found to be deleted in a family with XLRP. Our results indicate tissue-dependent regulation of alternative splicing of RPGR in mouse and man. The discovery of a retina-specific transcript may explain why phenotypic abberations in RP3 are confined to the eye.
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Affiliation(s)
- R Kirschner
- Max-Planck-Institut für molekulare Genetik, Ihnestrasse 73, D-14195 Berlin, Germany.
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45
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Abstract
Only changes in the DNA sequence manifesting deleterious effects at a functional level provide "disease-causing" mutations. Consequently, mutation-scanning techniques applied on a protein level would be most informative. However, because of a lack of functional knowledge and powerful methods, most currently applied techniques try to resolve mutations at the DNA level. The protein truncation test (PTT) provides a rare exception, targeting mutations that generate shortened proteins, mainly premature translation termination. PTT has several attractive characteristics, including pinpointing the site of a mutation, good sensitivity, a low false-positive rate, and, more importantly, the near-exclusive highlighting of disease-causing mutations. In addition, PTT facilitated the detection of a new mutation type, i.e., a sequence change generating a hypermutable region surfacing in the RNA. The main technical problems are related to the fact that PTT generally uses an RNA target, including the difficulties that arise from the potential differential expression and stability of the transcripts derived from the two alleles present. The PTT has hardly evolved from the method originally described, with multiplexing and N-terminal protein tagging forming the only innovating modifications. To implement high-throughput screens using PTT, major improvements of the basic procedure will be required.
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Affiliation(s)
- J T Den Dunnen
- MGC Department of Human Genetics and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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