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Bueschbell B, Manga P, Schiedel AC. The Many Faces of G Protein-Coupled Receptor 143, an Atypical Intracellular Receptor. Front Mol Biosci 2022; 9:873777. [PMID: 35495622 PMCID: PMC9039016 DOI: 10.3389/fmolb.2022.873777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/10/2022] [Indexed: 12/24/2022] Open
Abstract
GPCRs transform extracellular stimuli into a physiological response by activating an intracellular signaling cascade initiated via binding to G proteins. Orphan G protein-coupled receptors (GPCRs) hold the potential to pave the way for development of new, innovative therapeutic strategies. In this review we will introduce G protein-coupled receptor 143 (GPR143), an enigmatic receptor in terms of classification within the GPCR superfamily and localization. GPR143 has not been assigned to any of the GPCR families due to the lack of common structural motifs. Hence we will describe the most important motifs of classes A and B and compare them to the protein sequence of GPR143. While a precise function for the receptor has yet to be determined, the protein is expressed abundantly in pigment producing cells. Many GPR143 mutations cause X-linked Ocular Albinism Type 1 (OA1, Nettleship-Falls OA), which results in hypopigmentation of the eyes and loss of visual acuity due to disrupted visual system development and function. In pigment cells of the skin, loss of functional GPR143 results in abnormally large melanosomes (organelles in which pigment is produced). Studies have shown that the receptor is localized internally, including at the melanosomal membrane, where it may function to regulate melanosome size and/or facilitate protein trafficking to the melanosome through the endolysosomal system. Numerous additional roles have been proposed for GPR143 in determining cancer predisposition, regulation of blood pressure, development of macular degeneration and signaling in the brain, which we will briefly describe as well as potential ligands that have been identified. Furthermore, GPR143 is a promiscuous receptor that has been shown to interact with multiple other melanosomal proteins and GPCRs, which strongly suggests that this orphan receptor is likely involved in many different physiological actions.
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Affiliation(s)
- Beatriz Bueschbell
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Prashiela Manga
- Ronald O. Perelman Department of Dermatology, Grossman School of Medicine, New York University, New York City, NY, United States
| | - Anke C. Schiedel
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, Bonn, Germany
- *Correspondence: Anke C. Schiedel,
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Volk AE, Hedergott A, Preising M, Rading S, Fricke J, Herkenrath P, Nürnberg P, Altmüller J, von Ameln S, Lorenz B, Neugebauer A, Karsak M, Kubisch C. Biallelic mutations in L-dopachrome tautomerase (DCT) cause infantile nystagmus and oculocutaneous albinism. Hum Genet 2021; 140:1157-1168. [PMID: 33959807 DOI: 10.1007/s00439-021-02285-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/19/2021] [Indexed: 11/26/2022]
Abstract
Infantile nystagmus syndrome (INS) denominates early-onset, involuntary oscillatory eye movements with different etiologies. Nystagmus is also one of the symptoms in oculocutaneus albinism (OCA), a heterogeneous disease mainly caused by defects in melanin synthesis or melanosome biogenesis. Dopachrome tautomerase (DCT, also called TYRP2) together with tyrosinase (TYR) and tyrosin-related protein 1 (TYRP1) is one of the key enzymes in melanin synthesis. Although DCT´s role in pigmentation has been proven in different species, until now only mutations in TYR and TYRP1 have been found in patients with OCA. Detailed ophthalmological and orthoptic investigations identified a consanguineous family with two individuals with isolated infantile nystagmus and one family member with subtle signs of albinism. By whole-exome sequencing and segregation analysis, we identified the missense mutation c.176G > T (p.Gly59Val) in DCT in a homozygous state in all three affected family members. We show that this mutation results in incomplete protein maturation and targeting in vitro compatible with a partial or total loss of function. Subsequent screening of a cohort of patients with OCA (n = 85) and INS (n = 25) revealed two heterozygous truncating mutations, namely c.876C > A (p.Tyr292*) and c.1407G > A (p.Trp469*), in an independent patient with OCA. Taken together, our data suggest that mutations in DCT can cause a phenotypic spectrum ranging from isolated infantile nystagmus to oculocutaneous albinism.
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Affiliation(s)
- Alexander E Volk
- Institute of Human Genetics, University Medical Center Hamburg Eppendorf (UKE), Martinistr. 52, 20246, Hamburg, Germany.
| | - Andrea Hedergott
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, 50931, Cologne, Germany
| | - Markus Preising
- Department of Ophthalmology, Justus-Liebig-University Giessen, 35392, Giessen, Germany
| | - Sebastian Rading
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246, Hamburg, Germany
| | - Julia Fricke
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, 50931, Cologne, Germany
| | - Peter Herkenrath
- Department of Paediatrics, University of Cologne, 50931, Cologne, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics, University of Cologne, 50931, Cologne, Germany
| | - Janine Altmüller
- Cologne Center for Genomics, University of Cologne, 50931, Cologne, Germany
| | - Simon von Ameln
- Institute of Human Genetics, University of Ulm, 89081, Ulm, Germany
| | - Birgit Lorenz
- Department of Ophthalmology, Justus-Liebig-University Giessen, 35392, Giessen, Germany
- Department of Ophthalmology, University Hospital of Bonn, 53127, Bonn, Germany
| | - Antje Neugebauer
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, 50931, Cologne, Germany
| | - Meliha Karsak
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246, Hamburg, Germany
| | - Christian Kubisch
- Institute of Human Genetics, University Medical Center Hamburg Eppendorf (UKE), Martinistr. 52, 20246, Hamburg, Germany
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De Silva SR, Arno G, Robson AG, Fakin A, Pontikos N, Mohamed MD, Bird AC, Moore AT, Michaelides M, Webster AR, Mahroo OA. The X-linked retinopathies: Physiological insights, pathogenic mechanisms, phenotypic features and novel therapies. Prog Retin Eye Res 2020; 82:100898. [PMID: 32860923 DOI: 10.1016/j.preteyeres.2020.100898] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 08/07/2020] [Accepted: 08/21/2020] [Indexed: 02/08/2023]
Abstract
X-linked retinopathies represent a significant proportion of monogenic retinal disease. They include progressive and stationary conditions, with and without syndromic features. Many are X-linked recessive, but several exhibit a phenotype in female carriers, which can help establish diagnosis and yield insights into disease mechanisms. The presence of affected carriers can misleadingly suggest autosomal dominant inheritance. Some disorders (such as RPGR-associated retinopathy) show diverse phenotypes from variants in the same gene and also highlight limitations of current genetic sequencing methods. X-linked disease frequently arises from loss of function, implying potential for benefit from gene replacement strategies. We review X-inactivation and X-linked inheritance, and explore burden of disease attributable to X-linked genes in our clinically and genetically characterised retinal disease cohort, finding correlation between gene transcript length and numbers of families. We list relevant genes and discuss key clinical features, disease mechanisms, carrier phenotypes and novel experimental therapies. We consider in detail the following: RPGR (associated with retinitis pigmentosa, cone and cone-rod dystrophy), RP2 (retinitis pigmentosa), CHM (choroideremia), RS1 (X-linked retinoschisis), NYX (complete congenital stationary night blindness (CSNB)), CACNA1F (incomplete CSNB), OPN1LW/OPN1MW (blue cone monochromacy, Bornholm eye disease, cone dystrophy), GPR143 (ocular albinism), COL4A5 (Alport syndrome), and NDP (Norrie disease and X-linked familial exudative vitreoretinopathy (FEVR)). We use a recently published transcriptome analysis to explore expression by cell-type and discuss insights from electrophysiology. In the final section, we present an algorithm for genes to consider in diagnosing males with non-syndromic X-linked retinopathy, summarise current experimental therapeutic approaches, and consider questions for future research.
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Affiliation(s)
- Samantha R De Silva
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Gavin Arno
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony G Robson
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Ana Fakin
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Ljubljana University Medical Centre, Ljubljana, Slovenia
| | - Nikolas Pontikos
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Moin D Mohamed
- Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Alan C Bird
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Department of Ophthalmology, UCSF School of Medicine, San Francisco, CA, USA
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Omar A Mahroo
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, London, UK; Section of Ophthalmology, King's College London, UK; Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
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Gao X, Liu T, Cheng X, Dai A, Liu W, Li R, Zhang M. A novel GPR143 mutation in a Chinese family with X‑linked ocular albinism type 1. Mol Med Rep 2019; 21:240-248. [PMID: 31746431 PMCID: PMC6896309 DOI: 10.3892/mmr.2019.10813] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 09/19/2019] [Indexed: 11/24/2022] Open
Abstract
Ocular albinism type 1 (OA1) is a genetic disorder characterized by reduced eye pigmentation and nystagmus, which is often accompanied by decreased visual acuity, strabismus and other symptoms, whereas skin and hair color remain normal. The present study aimed to assess the clinical features and perform genotype analysis of a family with OA1, and to determine the disease-causing mutation. A total of 18 family members (nine affected patients and nine normal subjects) from Hainan, China, were recruited to the present study in December 2017. A detailed clinical ophthalmic examination was performed for all participants, including a visual acuity test, anterior segment slit lamp examination, eye fundus examination and optical coherence tomography. Mutations in the G protein-coupled receptor 143 (GPR143) gene were determined by DNA sequencing assays and polymerase chain reaction assays for deletions; all exon coding sequences, exons at the 5′- and 3′-ends, and non-coding region sequences of intron splicing were assessed. Within the family, nine male patients exhibited disease occurrence at the age of 0–6 months. All patients presented with different degrees of iris depigmentation, horizontal jerk nystagmus, foveal hypoplasia and reduced visual acuity. The fundus of only one patient exhibited choroid coloboma; in the remaining patients, their fundi exhibited different degrees of irregular retinal depigmentation. The mutation c.360+5G>T in the GPR143 gene was identified in this family. In conclusion, the present study identified the splicing mutation c.360+5G>T in the GPR143 gene in a Chinese family with OA1 and successfully identified the site. To the best of our knowledge, there have been no previous reports regarding this mutation in any major genome databases; therefore, this outcome may enrich the mutation spectrum of the GPR143 gene.
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Affiliation(s)
- Xuhui Gao
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China
| | - Tiecheng Liu
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China
| | - Xuan Cheng
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China
| | - Aiai Dai
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China
| | - Wei Liu
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China
| | - Runpu Li
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China
| | - Maonian Zhang
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing 100853, P.R. China
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Jia X, Yuan J, Jia X, Ling S, Li S, Guo X. GPR143 mutations in Chinese patients with ocular albinism type 1. Mol Med Rep 2017; 15:3069-3075. [PMID: 28339057 PMCID: PMC5428903 DOI: 10.3892/mmr.2017.6366] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 02/03/2017] [Indexed: 12/23/2022] Open
Abstract
The aim of the present study was to evaluate mutations of the G protein-coupled receptor 143 (GPR143) gene for ocular albinism type 1 (OA1) in Chinese patients. For the current study, 8 patients with OA1 were selected from the database of ocular genetic diseases. Genomic DNA of OA1 was prepared from venous leukocytes collected from the patients. Cycle sequencing was used to analyze the exons and adjacent introns of GPR143. The variation detected was analyzed by bidirectional DNA sequencing and further evaluated in 96 controls using heteroduplex-single strand conformational polymorphism analysis. Additionally, slit lamp photography of anterior segment, fundus photography and optical coherence tomography (OCT) were performed to identify the clinical features of OA1. In five patients with OA1, 5 GPR143 gene mutations were identified and four of them there were novel mutations. The screening rate is 62.5%, including c.333G>A (p.W111X), c.353G>A (p.G118E) (known mutation), C.658+2T>G (splice mutation), c.215_216insCGCTGC (p.71-72insAA) and c.17T>C (p. L6P). These mutations were absent in the 96 normal controls. Only one patient with OA1 in the present study was female. Patients with OA1 often have congenital nystagmus, refractive error, severe decline of visual acuity (from 0.1 to 0.4) and foveal hypoplasia. Different degrees of pigment loss were evident in the patients' iris and retina, whereas macular structure was not identified in the OCT examination. The findings of the present study expanded the gene mutation spectrum of GPR143 and investigated the clinical phenotype of patients with OA1 in the Chinese population. Additional evidence for clinical diagnosis was provided along with differential diagnosis and genetic counseling.
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Affiliation(s)
- Xiuhua Jia
- Department of Ophthalmology, The Third Affiliated Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Jin Yuan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xiaoyun Jia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Shiqi Ling
- Department of Ophthalmology, The Third Affiliated Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xiangming Guo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
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A cross-sectional examination of visual acuity by specific type of albinism. J AAPOS 2016; 20:419-424. [PMID: 27647118 DOI: 10.1016/j.jaapos.2016.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/07/2016] [Accepted: 06/10/2016] [Indexed: 11/22/2022]
Abstract
PURPOSE Reports of best-corrected visual acuity (BCVA) in albinism are often based on overlapping clinical phenotypes. BCVA in albinism has been shown to improve with age. This study reports a large cross-sectional investigation to determine whether BCVA differs by specific type of albinism when age-corrected. METHODS This retrospective review identified 170 individuals with a specific type of albinism identified by mutation(s) in a gene known to cause albinism (for OCA1, OCA2, and Hermansky-Pudlak syndrome ([HPS]) or a specific phenotype (white hair and no melanin pigment in OCA1A; pigmentary mosaicism in the obligate carriers for males with OA1). We recorded optotype binocular BCVA at final follow-up. Patients were age-grouped (2-5 years, 6-14 years, and ≥15 years) for comparison. RESULTS The greatest visual acuity deficit was found for OCA1A in all age groups. At age ≥15 years (n = 79), mean BCVA was 20/128 for OCA1A, 20/37 for OCA1B, 20/59 for OCA2, 20/63 for OA1, and 20/121 for HPS. Significant differences between BCVA at ≥15 years were found in the following: OCA1A vs OCA1B, OCA1A vs OCA2, OCA1A vs OA1, OCA1B vs HPS, OCA2 vs HPS, and OA1 vs HPS (P ≤ 0.02). CONCLUSIONS This study provides a large sample size and includes only those with a specific type of albinism. BCVA varies by albinism type, and there is overlap in BCVA, particularly in the younger age groups. For ages ≥15 years, there are significant differences in BCVA between several types of albinism.
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Deep intronic GPR143 mutation in a Japanese family with ocular albinism. Sci Rep 2015; 5:11334. [PMID: 26061757 PMCID: PMC4650666 DOI: 10.1038/srep11334] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/21/2015] [Indexed: 11/08/2022] Open
Abstract
Deep intronic mutations are often ignored as possible causes of human disease. Using whole-exome sequencing, we analysed genomic DNAs of a Japanese family with two male siblings affected by ocular albinism and congenital nystagmus. Although mutations or copy number alterations of coding regions were not identified in candidate genes, the novel intronic mutation c.659-131 T > G within GPR143 intron 5 was identified as hemizygous in affected siblings and as heterozygous in the unaffected mother. This mutation was predicted to create a cryptic splice donor site within intron 5 and activate a cryptic acceptor site at 41nt upstream, causing the insertion into the coding sequence of an out-of-frame 41-bp pseudoexon with a premature stop codon in the aberrant transcript, which was confirmed by minigene experiments. This result expands the mutational spectrum of GPR143 and suggests the utility of next-generation sequencing integrated with in silico and experimental analyses for improving the molecular diagnosis of this disease.
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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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Yan N, Liao X, Cai SP, Lan C, Wang Y, Zhou X, Yin Y, Yu W, Liu X. A novel nonsense mutation of the GPR143 gene identified in a Chinese pedigree with ocular albinism. PLoS One 2012; 7:e43177. [PMID: 22916221 PMCID: PMC3423421 DOI: 10.1371/journal.pone.0043177] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 07/18/2012] [Indexed: 02/05/2023] Open
Abstract
Background The purpose of this study was to elucidate the molecular basis of ocular albinism type I in a Chinese pedigree. Methodology/Principal Findings Complete ophthalmologic examinations were performed on 4 patients, 7 carriers and 17 unaffected individuals in this five-generation family. All coding exons of four-point-one (4.1), ezrin, radixin, moesin (FERM) domain-containing 7 (FRMD7) and G protein-coupled receptor 143 (GPR143) genes were amplified by polymerase chain reaction (PCR), sequenced and compared with a reference database. Ocular albinism and nystagmus were found in all patients of this family. Macular hypoplasia was present in the patients including the proband. A novel nonsense hemizygous mutation c.807T>A in the GPR143 gene was identified in four patients and the heterozygous mutation was found in seven asymptomatic individuals. This mutation is a substitution of tyrosine for adenine which leads to a premature stop codon at position 269 (p.Y269X) of GPR143. Conclusions/Significance This is the first report that p.Y269X mutation of GPR143 gene is responsible for the pathogenesis of familial ocular albinism. These results expand the mutation spectrum of GPR143, and demonstrate the clinical characteristics of ocular albinism type I in Chinese population.
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Affiliation(s)
- Naihong Yan
- State Key Laboratory of Biotherapy, Ophthalmic Laboratories, Department of Ophthalmology, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Xuan Liao
- State Key Laboratory of Biotherapy, Ophthalmic Laboratories, Department of Ophthalmology, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
- Department of Ophthalmology, North Sichuan Medical College, Nanchong, People’s Republic of China
| | - Su-ping Cai
- Shenzhen Eye Hospital, Jinan University, Shenzhen, People’s Republic of China
| | - Changjun Lan
- Department of Ophthalmology, North Sichuan Medical College, Nanchong, People’s Republic of China
| | - Yun Wang
- State Key Laboratory of Biotherapy, Ophthalmic Laboratories, Department of Ophthalmology, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Xiaomin Zhou
- State Key Laboratory of Biotherapy, Ophthalmic Laboratories, Department of Ophthalmology, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Yan Yin
- State Key Laboratory of Biotherapy, Ophthalmic Laboratories, Department of Ophthalmology, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Wenhan Yu
- State Key Laboratory of Biotherapy, Ophthalmic Laboratories, Department of Ophthalmology, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, People’s Republic of China
| | - Xuyang Liu
- Shenzhen Eye Hospital, Jinan University, Shenzhen, People’s Republic of China
- * E-mail:
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Xiao X, Zhang Q. Iris hyperpigmentation in a Chinese family with ocular albinism and the GPR143 mutation. Am J Med Genet A 2009; 149A:1786-8. [PMID: 19610097 DOI: 10.1002/ajmg.a.32818] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
X-linked ocular albinism (OA1) is the most common form of ocular albinism. Affected males are characterized by nystagmus, impaired visual acuity, iris hypopigmentation with translucency, fundus hypopigmentation, macular hypoplasia, and normally pigmented skin and hair. However, OA1 has rarely been reported in China. Here, we report on a Chinese family with OA1 and partial deletion of GPR143. An unusual phenotype of iris hyperpigmentation without translucency was observed in the male patient and the carrier mother. There was apparent mosaic pigmentation of the fundus. Our results demonstrate atypical manifestation of OA1 that might enrich our knowledge of phenotypic variation of OA1 among the Chinese population.
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Affiliation(s)
- Xueshan Xiao
- Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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Kumar A, Gottlob I. Diagnosis of idiopathic infantile nystagmus and ocular albinism: a clinical challenge. EXPERT REVIEW OF OPHTHALMOLOGY 2009. [DOI: 10.1586/eop.09.31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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12
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Wong L, O'Donnell FE, Richard Green W. Giant pigment granules in the retinal pigment epithelium of a fetus with X-linked ocular albinism. ACTA ACUST UNITED AC 2009. [DOI: 10.3109/13816818309007149] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Oetting WS. New insights into ocular albinism type 1 (OA1): Mutations and polymorphisms of the OA1 gene. Hum Mutat 2002; 19:85-92. [PMID: 11793467 DOI: 10.1002/humu.10034] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Albinism ocular type 1 (OA1) is an X-linked type of albinism that mainly effects pigment production in the eye, resulting in hypopigmentation of the retina, nystagmus, strabismus, foveal hypoplasia, abnormal crossing of the optic fibers, and reduced visual acuity. The OA1 gene is located on chromosome Xp22.32 and the coding sequence is divided into nine exons. The protein is an integral transmembrane protein that has weak similarities to G protein-coupled receptors. A total of 25 missense, two nonsense, nine frameshift, and five splicing mutations have been reported in the OA1 gene associated with OA1. There are also several deletions of some or all exons of the OA1 gene with deletions of exon 2 resulting from unequal crossing-over, due to flanking Alu repeats. Mutation and polymorphism data on this gene is available from the International Albinism Center - Albinism Database web site (http://www.cbc.umn.edu/tad).
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Affiliation(s)
- William S Oetting
- Department of Medicine and Institute of Human Genetics, University of Minnesota, Minneapolis, Minnesota, USA
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14
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Preising M, Op de Laak JP, Lorenz B. Deletion in the OA1 gene in a family with congenital X linked nystagmus. Br J Ophthalmol 2001; 85:1098-103. [PMID: 11520764 PMCID: PMC1724103 DOI: 10.1136/bjo.85.9.1098] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To elucidate the molecular genetic defect of X linked congenital nystagmus associated with macular hypoplasia in three white males of a three generation family with clear features of ocular albinism in only one of them. METHODS A three generation family with congenital nystagmus following X linked inheritance, and associated with macular hypoplasia was clinically examined (three males and two obligate carriers). Flash VEP was performed to look for albino misrouting. DNA samples were subjected to PCR and subsequent analysis using SSCP for all exons of the OA1 gene. RT-PCR was performed on a mRNA preparation from a naevus from one patient. PCR products presenting divergent banding patterns in SSCP and from the RT-PCR were sequenced directly using cycle sequencing with fluorescent chain termination nucleotides and electrophoresis in a capillary sequencer. RESULTS The index case (patient 1, IV.1) was diagnosed with X linked OA1 at the age of 3 months because of typical clinical features: congenital nystagmus, iris translucency, macular hypoplasia, fundus hypopigmentation, normal pigmentation of skin and hair, and typical carrier signs of OA1 in his mother and maternal grandmother. Pigmentation of the iris and fundus had increased at the last examination at age 4 years. Albino misrouting was present at this age. In the maternal uncle (III.3, 51 years) who also suffered from congenital nystagmus there was clear macular hypoplasia and stromal focal hypopigmentation of the iris but no iris translucency or fundus hypopigmentation. Patient 3 (II.3, 79 years, maternal uncle of patient III.3) had congenital nystagmus and was highly myopic. The fundus appearance was typical for excessive myopia including macular changes. The iris did not show any translucency. Molecular genetic analysis revealed a novel 14 bp deletion of the OA1 gene at nt816 in exon 6. The mutation abolishes four amino acids (Leu 253-Ile-Ile-Cys) and covers the splice site. Nucleotides 814/815 are used as a new splice donor thus producing a frame shift in codon 252 and a new stop codon at codon 259. CONCLUSIONS Macular hypoplasia without clinically detectable hypopigmentation as the only sign of X linked OA1 has been reported occasionally in African-American, Japanese, and white patients. The present family shows absent hypopigmentation in two patients of a white family with a deletion in the OA1 gene. We propose a model of OA1 that allows increase of pigmentation with age. We hypothesise that macular hypoplasia in all forms of albinism depends on the extracellular DOPA level during embryogenesis, and that in OA1 postnatal normalisation of the extracellular DOPA level due to delayed distribution and membrane budding/fusion of melanosomes in melanocytes results in increasing pigmentation.
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Affiliation(s)
- M Preising
- Department of Paediatric Ophthalmology, Strabismology, and Ophthalmogenetics, University of Regensburg, 93042 Regensburg, Germany.
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15
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Schnur RE, Gao M, Wick PA, Keller M, Benke PJ, Edwards MJ, Grix AW, Hockey A, Jung JH, Kidd KK, Kistenmacher M, Levin AV, Lewis RA, Musarella MA, Nowakowski RW, Orlow SJ, Pagon RS, Pillers DA, Punnett HH, Quinn GE, Tezcan K, Wagstaff J, Weleber RG. OA1 mutations and deletions in X-linked ocular albinism. Am J Hum Genet 1998; 62:800-9. [PMID: 9529334 PMCID: PMC1377018 DOI: 10.1086/301776] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
X-linked ocular albinism (OA1), Nettleship-Falls type, is characterized by decreased ocular pigmentation, foveal hypoplasia, nystagmus, photodysphoria, and reduced visual acuity. Affected males usually demonstrate melanin macroglobules on skin biopsy. We now report results of deletion and mutation screening of the full-length OA1 gene in 29 unrelated North American and Australian X-linked ocular albinism (OA) probands, including five with additional, nonocular phenotypic abnormalities (Schnur et al. 1994). We detected 13 intragenic gene deletions, including 3 of exon 1, 2 of exon 2, 2 of exon 4, and 6 others, which span exons 2-8. Eight new missense mutations were identified, which cluster within exons 1, 2, 3, and 6 in conserved and/or putative transmembrane domains of the protein. There was also a splice acceptor-site mutation, a nonsense mutation, a single base deletion, and a previously reported 17-bp exon 1 deletion. All patients with nonocular phenotypic abnormalities had detectable mutations. In summary, 26 (approximately 90%) of 29 probands had detectable alterations of OA1, thus confirming that OA1 is the major locus for X-linked OA.
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Affiliation(s)
- R E Schnur
- Division of Genetics, Children's Regional Hospital, Camden, NJ 08103, USA.
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16
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Lam BL, Fingert JH, Shutt BC, Singleton EM, Merin LM, Brown HH, Sheffield VC, Stone EM. Clinical and molecular characterization of a family affected with X-linked ocular albinism (OA1). Ophthalmic Genet 1997; 18:175-84. [PMID: 9457748 DOI: 10.3109/13816819709041432] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Thirty-one members of a family affected with X-linked ocular albinism (OA1) were studied to characterize the clinical phenotype and identify the disease-causing mutation. The family members were examined with ophthalmoscopy, electroretinography, and Goldmann perimetry. Linkage analysis was performed with markers from the OA1 locus. Exons 2 and 8 of the OA1 gene were assayed with the polymerase chain reaction (PCR). The six affected males had visual acuities ranging from 20/40 to 20/200. All had nystagmus, iris transillumination, and foveal hypoplasia. The eldest affected male had 20/40 vision and was asymptomatic. The level of the visual acuity of the affected males was not related to the degree of retinal pigmentation. All seven female carriers had normal visual function but were found to have iris transillumination defects and variable retinal pigmentary appearance ranging from minimal pigmentary disturbance, patchy and diffuse hypopigmentation, to classic 'mud-splattered' appearance. Linkage analysis was consistent with a disease-causing mutation at the OA1 locus. PCR analysis revealed a deletion which includes at least the portion of the OA1 gene between exons 2 and 8. Affected males with X-linked ocular albinism can have a visual disability that ranges from almost none to legal blindness, and the female carriers can have variable retinal pigmentary appearance. Mutation screening of the OA1 gene can be used to confirm the diagnosis in isolated males of some families, and genetic linkage analysis can be used to accurately identify carriers even when the specific mutation cannot be identified.
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Affiliation(s)
- B L Lam
- Bascom Palmer Eye Institute, University of Miami, Florida, USA
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17
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Shiono T, Tsunoda M, Chida Y, Nakazawa M, Tamai M. X linked ocular albinism in Japanese patients. Br J Ophthalmol 1995; 79:139-43. [PMID: 7696233 PMCID: PMC505044 DOI: 10.1136/bjo.79.2.139] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Thirteen affected Japanese male patients and 13 female carriers with X linked ocular albinism from seven families were examined to assess their clinical findings and to compare them with those of white and black patients. Affected Japanese patients had poor visual acuity, horizontal nystagmus, macular hypoplasia, and loss of stereopsis. Some affected patients had non-albinotic fundus with moderate pigmentation. The amount of pigment in the fundus varied among affected patients and appeared to be between that of the white and black patients. All affected patients had brown irides that show no translucency. Interestingly, two affected patients had megalocornea and a third affected patient had posterior embryotoxon. All female carriers exhibited good visual acuity, normal eye position, stereopsis, brown irides without translucency, and the typical mosaic pattern in the fundus. The pigmented iris and fundus made the correct diagnosis of these affected patients difficult. Nine affected patients (70%) had been diagnosed initially as having congenital nystagmus, with or without macular hypoplasia, until they were reviewed for this study.
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Affiliation(s)
- T Shiono
- Department of Ophthalmology, Tohoku University School of Medicine, Aoba-ku, Sendai, Japan
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18
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Shastry BS. Recent developments in certain X-linked genetic eye disorders. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1182:119-27. [PMID: 8357842 DOI: 10.1016/0925-4439(93)90131-j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Over the past few years, genetic diseases of the ocular system have become very active and fast-growing research areas in the vision field. The rapid development of the recombinant DNA techniques together with somatic cell genetics, during the last two decades has fueled this progress. As a result, many genetic disease genes have been localized in the human chromosome and several of them have been isolated and characterized. These and other studies have profoundly enriched our basic understanding of genetic eye disorders. Although gene replacement therapy, prenatal diagnosis and carrier detection have not been extensively tried for genetic eye diseases, such attempts will now be feasible. Molecular analyses made it clear that there are many challenging problems that need attention. This report highlights some of these initial developments, particularly on the X-linked major genetic eye diseases. In order to help the beginners and general audience, a brief description of the clinical pathology and the molecular probes used to locate the genetic defects of certain disorders are presented. Disorders are arranged according to their linkage from telomere to telomere on the chromosome to give a coherent structure. It is hoped that this information is useful and of general interest for the beginners, established investigators and ophthalmologists.
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Affiliation(s)
- B S Shastry
- Eye Research Institute of Oakland University, Rochester, MI 48309-4401
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19
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Charles SJ, Green JS, Grant JW, Yates JR, Moore AT. Clinical features of affected males with X linked ocular albinism. Br J Ophthalmol 1993; 77:222-7. [PMID: 8494858 PMCID: PMC504486 DOI: 10.1136/bjo.77.4.222] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Seventy four males affected by X linked ocular albinism (XLOA) from 19 pedigrees were examined to assess phenotypic variation and visual prognosis. Nystagmus was present in all cases except one. Best visual acuity ranged from 6/9 to 6/60; 79.7% could see 6/36 or better; most could read N5. Marked iris translucency and foveal hypoplasia were present in all cases. Posterior embryotoxon was present in 30% and dysplastic optic discs were often seen. Pigmentation of the posterior pole was associated with better visual acuity. XLOA is under-diagnosed: almost 20% of cases had been previously diagnosed as having congenital nystagmus until reviewed in this study.
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Affiliation(s)
- S J Charles
- Addenbrooke's Hospital, Cambridge Department of Ophthalmology
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20
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Pinckers A, Cruysberg JRM, Renier WO. Delayed myelination of the optic nerve and pseudo optic atrophy of Beauvieux. Neuroophthalmology 1993. [DOI: 10.3109/01658109309038146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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21
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Rose NC, Menacker SJ, Schnur RE, Jackson L, McDonald-McGinn DM, Stump T, Emanuel BS, Zackai EH. Ocular albinism in a male with del (6)(q13-q15): candidate region for autosomal recessive ocular albinism? AMERICAN JOURNAL OF MEDICAL GENETICS 1992; 42:700-5. [PMID: 1632442 DOI: 10.1002/ajmg.1320420515] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We describe a boy with an interstitial deletion of 6(q13-q15) and include "coarse" facial features, upslanting palpebral fissures, thin vermilion border of the upper lip, elongated philtrum, developmental delay, and profound hypotonia. The child's eye findings, pedigree, paucity of maternal ocular changes, and lack of melanin macroglobules in the skin suggest that this individual's phenotype is clinically similar to that of autosomal recessive ocular albinism. Though it is possible that this deletion and his ophthalmic disorder are coincidental, we postulate that the ocular albinism may be due to hemizygosity for a paternally derived ocular albinism gene located on chromosome 6 in the region q13-q15. This patient's deletion is secondary to a recombination of a maternal intrachromosomal inverted insertion of this region. Of the 7 reported 6q1 deletions, this is the only case that is due to a familial chromosome rearrangement.
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Affiliation(s)
- N C Rose
- Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia 19104
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22
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Abstract
A 10-year-old Chinese boy with the characteristic skin manifestations of dyschromatosis universalis is described. In addition, the patient had congenital nystagmus with poor visual acuity, and ophthalmological examination revealed foveal hypoplasia and albino-like fundi. Histopathology showed giant pigment granules in the skin. Based upon the finding of giant pigment granules in clinically normal skin of the patient's mother, the patient was diagnosed as a case of dyschromatosis universalis with X-linked ocular albinism. To the best of our knowledge, this is the first documented case of this combination.
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Affiliation(s)
- J H Yang
- Department of Dermatology, National Yang-Ming Medical College, Taipei, Taiwan, Republic of China
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23
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Summers CG, Creel D, Townsend D, King RA. Variable expression of vision in sibs with albinism. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 40:327-31. [PMID: 1951438 DOI: 10.1002/ajmg.1320400316] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Oculocutaneous albinism is defined by the presence of cutaneous and ocular hypopigmentation, the latter associated with nystagmus, iris transillumination, reduced retinal pigment, foveal hypoplasia, and misrouting of the optic fibers at the chiasm. The visual acuity is variable but almost always reduced. We report on two brothers with oculocutaneous albinism and markedly different visual acuity. One brother has a visual acuity of 20/100, while the second has similar cutaneous pigmentation and visual acuity of 20/20 and had not previously been recognized as having oculocutaneous albinism. Both brothers have foveal hypoplasia and misrouting of the optic fibers at the chiasm. Biochemical analysis suggests that this is a tyrosinase-related type of oculocutaneous albinism. This study demonstrates that careful observation of foveal development in relatives with normal vision is necessary to detect all individuals with albinism in a family. A suspected diagnosis of albinism may be confirmed when the visual-evoked potentials show excessive decussation of the optic fibers at the chiasm.
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Affiliation(s)
- C G Summers
- Department of Ophthalmology, University of Minnesota, Minneapolis 55455
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24
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Schnur RE, Nussbaum RL, Anson-Cartwright L, McDowell C, Worton RG, Musarella MA. Linkage analysis in X-linked ocular albinism. Genomics 1991; 9:605-13. [PMID: 1674724 DOI: 10.1016/0888-7543(91)90353-g] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We studied the linkage of X-linked Nettleship-Falls ocular albinism (OA1) to Xp22.1-Xp22.3 RFLPs at 12 loci in five families, including one in which OA1 cosegregates with a deletion of steroid sulfatase (STS). We found evidence for tight linkage of OA1 to the Xp22.3 loci DXS143, STS, and DXS452. DXS452, a newly described polymorphism detected by the probe E25B1.8, is part of the sequence family "DXS278" (pCRI-S232), but represents a single genetic locus. Every female in this study was heterozygous for the DXS452 RFLP. Thus, this marker will be extremely useful for family studies and genetic counseling. Analysis of individual recombinations suggests that OA1 maps between DXS143 and DXS85. Multipoint linkage analysis was consistent with this localization but was not statistically significant. These data suggest that OA1 lies proximal to the deletion in a previously described family with OA1 and STS deletion, but maps within the Xp22.3-Xp22.2 region.
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Affiliation(s)
- R E Schnur
- Department of Human Genetics, University of Pennsylvania School of Medicine, Philadelphia
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25
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Lang GE, Rott HD, Pfeiffer RA. X-linked ocular albinism. Characteristic pattern of affection in female carriers. OPHTHALMIC PAEDIATRICS AND GENETICS 1990; 11:265-71. [PMID: 2096354 DOI: 10.3109/13816819009015712] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The authors report on a family with X-linked ocular albinism. Examined were one of three affected males and eight females. Six women were carriers and showed iris retroillumination and typical abnormalities of the fundus. The patchy or striated hypopigmentation of the retinal pigment epithelium is thought to be due to random inactivation of the paternal or maternal X-chromosome respectively. The pattern of affection however represents a nonrandom embryological developmental pattern of the retinal pigment epithelium.
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Affiliation(s)
- G E Lang
- Augenklinik mit Poliklinik, University of Erlangen-Nürnberg, F.R.G
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26
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Bergen AA, Samanns C, Van Dorp DB, Ferguson-Smith MA, Gal A, Bleeker-Wagemakers EM. Localization of the X-linked ocular albinism gene (OA1) between DXS278/DXS237 and DXS143/DXS16 by linkage analysis. OPHTHALMIC PAEDIATRICS AND GENETICS 1990; 11:165-70. [PMID: 2280973 DOI: 10.3109/13816819009020975] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Linkage analysis was performed in six families segregating for X-linked ocular albinism of the Nettleship-Falls type using four polymorphic DNA markers from the distal Xp. Linkage was found between the disease locus (OA1) and the loci DXS237 (theta max = 0.06, Zmax = 2.82), DXS278 (theta max = 0.03, Zmax = 5.27) and DXS16 (theta max = 0.10, Zmax = 2.33). The analysis of multiple informative meioses suggests that OA1 maps between DXS278/DXS237 and DXS143/DXS16. Multipoint linkage analysis slightly favours the order DXS278/DXS237-OA1-DXS16. These data refine the genetic localization of OA1 and may be useful for carrier detection in X-linked ocular albinism by DNA analysis.
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Affiliation(s)
- A A Bergen
- The Netherlands Ophthalmic Research Institute, Amsterdam
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27
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Dickinson AJ, Fielder AR, Young ID, Duckett DP. Ocular findings in Angelman's (happy puppet) syndrome. OPHTHALMIC PAEDIATRICS AND GENETICS 1990; 11:1-6. [PMID: 2348977 DOI: 10.3109/13816819009012942] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Patients with Angelman's syndrome have been reported to have ocular hypopigmentation and a number are now known to have a microdeletion of chromosome 15q 11----13. Detailed ocular examination of eight new cases revealed normal visual acuity and foveal reflexes, but a pigmentary deficiency which is limited to the choroid and iris stroma--both of neural crest origin. Patients with Prader-Willi syndrome have similar ocular features and many have a microdeletion of chromosome 15q 11----13. It is therefore possible that this region may influence neural crest development.
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Affiliation(s)
- A J Dickinson
- Department of Ophthalmology, Leicester Royal Infirmary, UK
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Affiliation(s)
- C J Witkop
- Department of Oral Pathology and Genetics, University of Minnesota School of Dentistry, Minneapolis
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Maguire AM, Maumenee IH. Iris pigment mosaicism in carriers of X-linked ocular albinism cum pigmento. Am J Ophthalmol 1989; 107:298-9. [PMID: 2923159 DOI: 10.1016/0002-9394(89)90319-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- A M Maguire
- Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, MD 21205
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Abstract
Albinism is not a single entity but represents a heterogenous group of inherited disorders of pigmentation. Despite a wide variety of manifestations, all forms of albinism are characterized by several ocular features, including: nystagmus, photophobia, reduced visual acuity and a lack of stereopsis. It is the intention of this review to describe and discuss the clinical implications of albinism with particular emphasis placed on these ocular features and their effects on visual performance. Various techniques that may be employed to aid the albino will also be described.
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Affiliation(s)
- R Abadi
- Department of Ophthalmic Optics, UMIST, Manchester, UK
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31
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Abstract
A review of the basics of pigment cell biology is followed by a discussion of the characteristics of several disorders of hypopigmentation. By determining such features as inheritance pattern, time of onset (congenital, childhood, adulthood), natural history (stable vs progressive), type of pigment loss (diffuse or circumscribed), distribution of lesions (generalized vs localized), degree of pigment loss (incomplete or complete), number of melanocytes, if any, in biopsy specimens of affected areas, type of melanocytic dysfunction, and associated inflammation or infection, one can classify the disorders of hypopigmentation. The proposed pathophysiology for each disorder of hypomelanosis is presented.
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Affiliation(s)
- J L Bolognia
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06510
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Abstract
UNLABELLED After a 4-year multidisciplinary study of albinism our findings will be presented here. Over a hundred albinos were examined, together with their heterozygote family members. Given this substantial patient and subject sample we were provided with the opportunity to: evaluate the results of standard diagnostic procedures, for example pedigree analysis, ocular and clinical examination; determine the diagnostic value of biochemical, and ultrastructural tests; and develop a new and viable albino diagnostic protocol, particularly for electrophysiological examination. In the conclusions the following subjects are in order: DIAGNOSIS Our most important finding up till now is that normally pigmented people who do not look like albinos can in fact be albinos. DIFFERENTIAL DIAGNOSIS It appears that patients with autosomal recessive albinism can be normally pigmented, and patients with X-linked albinism can be severely hypopigmented. We therefore propose to abandon the terms oculo-cutaneous albinism (OCA), and X-linked ocular albinism (XOA), and use the terms autosomal recessive albinism, and X-linked albinism instead. X-linked albinism Forsius-Eriksson type (XOAF): We assume that XOAF does not represent a true form of albinism. CLASSIFICATION Our results indicate that the phenotypical albino classification, which was a base for Witkop et al. (1978) to also obtain a genetical classification, supported by the hairbulb test, has not proved to be useful for the classification of tyrosinase negative (TNOCA), tyrosinase positive oculocutaneous albinism (TPOCA), and autosomal recessive ocular albinism (AROA) as genetically distinct forms. Prevalence: Our prevalence estimate for all forms of albinism is at least 1:15,000, about 10% of the albinos have X-linked albinism. DEFINITION We want to modify the albino definition as a hereditary and congenital inborn error of metabolism related to the pigment cell, and resulting in a systemic disorder that is characterized by anomalies of eyes, and hypopigmentation in most cases or absence of pigment in skin, hair, and eyes, and of which the neuro-anatomical consequences are the most characteristic.
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Abstract
Albinism is a condition in which the pigment melanin may not be synthesized from tyrosine. The fundus photographs of 24 eyes of 12 patients with the clinical diagnosis of either ocular or oculocutaneous albinism were reviewed. We observed two findings that to our knowledge have not been reported previously. Eighteen eyes of ten patients had prominent retinal vessels coursing through the putative macular area instead of arching around it. Large noncilioretinal vessels extended from the disc to the dysplastic "foveal zone" in eight eyes of five patients. Typical optic nerve hypoplasia (ONH) was seen in six eyes of four patients; features suggestive of ONH were present in an additional ten eyes of six patients. The cross-over (sharing) of clinical features between albinism and aniridia is striking and raises questions about pathophysiologic mechanisms.
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Abstract
Albinism is the term applied to a heterogeneous group of genetically determined disorders characterized by hypopigmentation and affecting the eyes. After describing the clinical features of albinism in general, the authors discuss the various forms of oculocutaneous albinism, ocular albinism, and albinoidism that are of interest to the ophthalmologist. Emphasis is placed on the ocular features of each form. The visual pathway abnormalities and the clinical management of albinism are discussed.
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Guillery RW, Hickey TL, Kaas JH, Felleman DJ, Debruyn EJ, Sparks DL. Abnormal central visual pathways in the brain of an albino green monkey (Cercopithecus aethiops). J Comp Neurol 1984; 226:165-83. [PMID: 6330179 DOI: 10.1002/cne.902260203] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The visual pathways of an albino green monkey have been studied electrophysiologically and by autoradiographic methods. The monkey had a white coat and pink eyes; it had a strabismus and a nystagmus. When comparisons were made with normal macaque and green monkeys, several abnormalities could be defined. In the retina there was no foveal pit. A whole mount preparation showed a central area of high ganglion cell density in which the ganglion cells were significantly larger than the most central ganglion cells of a normal monkey. More peripheral retinal areas showed an apparently normal distribution of ganglion cell sizes and packing densities. Within the optic tract the number of uncrossed retinofugal fibers was less than normal, the part of the tract that represents central vision showing almost no uncrossed component. The uncrossed input to the lateral geniculate nucleus and to the superior colliculus was similarly reduced. Regions normally receiving ipsilateral afferents from the central retina were innervated exclusively by crossed afferents. The pathways to the magnocellular geniculate layers showed a more extensive abnormality than did the pathways to the parvicellular layers. Not only were the afferents to the geniculate layers abnormal, but the laminar pattern in the nucleus was also clear than normal in some parts of the nucleus, and there were a number of abnormal laminar fusions. Within the visual cortex it was possible to demonstrate a normal mapping of the contralateral visual field through the contralateral nasal retina and through the peripheral parts of the ipsilateral temporal retina. The central parts of the temporal retina mapped abnormally in the contralateral visual cortex, so that there was a monocular map of the central parts of the visual field forming as a mirror reversal of the normal map. The normal map of the contralateral hemifield formed columns that alternated with the abnormal map of the ipsilateral hemifield. The peripheral parts of the visual field were represented as ocular dominance columns, demonstrable electrophysiologically and also by the transneuronal transport of 3H-proline.
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Abstract
The many diseases and disorders that frequently have ophthalmologic implications in the pediatric age group are discussed.
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39
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Jaeger C, Jay B. X-linked ocular albinism: a family containing a manifesting heterozygote, and an affected male married to a female with autosomal recessive ocular albinism. Hum Genet 1981; 56:299-304. [PMID: 7239514 DOI: 10.1007/bf00274683] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A pedigree of X-linked ocular albinism is presented containing nine affected males and 10 heterozygous females. One carrier female showed ocular changes similar to those of affected males. She is considered to be a manifesting heterozygote, a situation explained by the Lyon hypothesis. One affected male married a female with autosomal recessive ocular albinism and produced one daughter with the fundus changes of the carrier state of X-linked ocular albinism, and one son with normal eyes. The daughter did not show any evidence of the additive effect of the two different genes for X-linked and autosomal recessive ocular albinism.
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O'Donnell FE, Green WR, McKusick VA, Forsius H, Eriksson AW. Forsius-Eriksson syndrome: its relation to the Nettleship-Falls X-linked ocular albinism. Clin Genet 1980; 17:403-8. [PMID: 7398111 DOI: 10.1111/j.1399-0004.1980.tb00170.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
On the basis of clinical data, it had previously been proposed that the Forsius-Eriksson syndrome is identical to Nettleship-Falls X-linked ocular albinism. We performed biopsies of clinically-normal skin in patients with the Forsius-Eriksson syndrome to look for the abnormal melanosomes characteristic of Nettleship-Falls X-linked ocular albinism. There were no abnormalities in the melanosomes of patients with Forsius-Eriksson syndrome. Thus, this syndrome is distinct from the Nettleship-Falls disorder.
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Abstract
Examination of clinically normal skin from four patients with X-linked ocular albinism of the Nettleship-Falls type by light and electron microscopy revealed the presence of macromelanosomes in some melanocytes and keratinocytes. Measuring up to 5 micron many of the abnormal melanosomes showed a concentrically laminated structure suggestive of a phasic growth pattern. Epidermis from three female carriers contained similar but fewer macromelanosomes. These findings indicate that skin biopsy could be of value not only in confirming the diagnosis of ocular albinism in affected males, but also to establish carrier status in asymptomatic females.
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Abstract
Visually evoked potentials recorded from two types of human ocular albinos demonstrated significant hemispheric asymmetry following monocular stimulation. The asymmetry is indicative of disorganization of retinogeniculostriate projections similar to that reported for mammals with total albinism. Abnormal optic projections are associated with lack of ocular pigment and are not associated with any specific generalized pigment defect.
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