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Polubothu S, Kinsler VA. Response to Torchia. J Invest Dermatol 2023; 143:2537-2538. [PMID: 37295492 DOI: 10.1016/j.jid.2023.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 05/06/2023] [Indexed: 06/12/2023]
Affiliation(s)
- Satyamaanasa Polubothu
- Mosaicism and Precision Medicine Laboratory, The Francis Crick Institute, London, UK; Paediatric Dermatology, Great Ormond Street Hospital, London, UK; Genetics & Genomic Medicine, UCL GOS Institute of Child Health, London, UK
| | - Veronica A Kinsler
- Mosaicism and Precision Medicine Laboratory, The Francis Crick Institute, London, UK; Paediatric Dermatology, Great Ormond Street Hospital, London, UK; Genetics & Genomic Medicine, UCL GOS Institute of Child Health, London, UK.
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2
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Kuht HJ, Thomas MG, McLean RJ, Sheth V, Proudlock FA, Gottlob I. Abnormal foveal morphology in carriers of oculocutaneous albinism. Br J Ophthalmol 2023; 107:1202-1208. [PMID: 35379600 PMCID: PMC10359511 DOI: 10.1136/bjophthalmol-2020-318192] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/18/2022] [Indexed: 01/04/2023]
Abstract
BACKGROUND/AIMS To investigate the foveal morphology in carriers of oculocutaneous albinism (OCA) using spectral domain optical coherence tomography (SD-OCT). A cross-sectional, observational study. METHODS Handheld SD-OCT (Envisu C2300) was used to acquire horizontal scans through the centre of the fovea in biological parents of patients with OCA (n=28; mean age±SD=40.43±8.07 years) and age-matched and ethnicity-matched controls (n=28; mean age±SD=38.04±10.27 years). Sequence analysis was performed for variants in known genes associated with OCA. Best-corrected visual acuity (BCVA), presence of foveal hypoplasia and grade, foveal, parafoveal and perifoveal thickness measurements of total retinal layers (TRL), inner retinal layers (IRL) and outer retinal layers (ORL) thickness were measured. RESULTS Foveal hypoplasia was identified in 32.14% of OCA carriers; grade 1 in all cases. OCA carriers demonstrated significant thicker TRL thickness (median difference: 13.46 µm, p=0.009) and IRL thickness (mean difference: 8.98 µm, p<0.001) at the central fovea compared with controls. BCVA of carriers was between -0.16 and 0.18 logMAR (mean: 0.0 logMAR). No significant differences in BCVA was noted between OCA carriers or controls (p=0.83). In the OCA carriers, we identified previously reported pathogenic variants in TYR, OCA2 and SLC45A2, novel OCA2 variants (n=3) and heterozygosity of the pathogenic TYR haplotype. CONCLUSION We have, for the first time, identified foveal abnormalities in OCA carriers. This provides clinical value, particularly in cases where limited phenotype data are available. Our findings raise the possibility that previously reported mild cases of foveal hypoplasia or isolated foveal hypoplasia could correspond to OCA carrier status.
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Affiliation(s)
- Helen J Kuht
- Ulverscroft Eye Unit, Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Mervyn G Thomas
- Ulverscroft Eye Unit, Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Rebecca J McLean
- Ulverscroft Eye Unit, Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Viral Sheth
- Ulverscroft Eye Unit, Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Frank A Proudlock
- Ulverscroft Eye Unit, Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Irene Gottlob
- Ulverscroft Eye Unit, Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
- Cooper Medical School of Rowan University, Cooper Neurological Institute, Camden, New Jersey, USA
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Ullah MI. Clinical and Mutation Spectrum of Autosomal Recessive Non-Syndromic Oculocutaneous Albinism (nsOCA) in Pakistan: A Review. Genes (Basel) 2022; 13:genes13061072. [PMID: 35741834 PMCID: PMC9222488 DOI: 10.3390/genes13061072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/09/2022] [Accepted: 06/13/2022] [Indexed: 02/01/2023] Open
Abstract
Oculocutaneous albinism (OCA) is an autosomal recessive syndromic and non-syndromic defect with deficient or a complete lack of the melanin pigment. The characteristics of OCA appears in skin, hair, and eyes with variable degree of pigmentation. Clinical manifestations of OCA include nystagmus, photophobia, reduced visual acuity, hypo-plastic macula, and iris trans-illumination. There are eight OCA types (OCA1–8) documented with non-syndromic characteristics. Molecular studies identified seven genes linked to the OCA phenotype (TYR, OCA2, TYRP1, SLC45A2, SLC24A5, C10orf11, and DCT) and one locus (OCA5) in consanguineous and sporadic albinism. The complications of OCA result in skin cancer and variable syndromes such as Hermansky–Pudlak syndrome (HPS) Chediak–Higashi syndrome (CHS). In the Pakistani population, autosomal recessive non-syndromic OCA is common and is associated with a large number of consanguineous families, and mutations in genes of non-syndromic types are reported. This review highlights the updates on the genetic mutation of OCA genes reported from Pakistani families. Several studies reported the genetic mutations in OCA1, OCA2, OCA3, OCA4, and OCA6 albinism in Pakistani families. A locus, OCA5, was also reported from the Pakistani population, but the gene has not been identified. A new type of OCA8 was identified due to the DCT gene mutation, and it is also reviewed here.
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Affiliation(s)
- Muhammad Ikram Ullah
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakaka 75471, Aljouf, Saudi Arabia
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4
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Lin S, Sanchez-Bretaño A, Leslie JS, Williams KB, Lee H, Thomas NS, Callaway J, Deline J, Ratnayaka JA, Baralle D, Schmitt MA, Norman CS, Hammond S, Harlalka GV, Ennis S, Cross HE, Wenger O, Crosby AH, Baple EL, Self JE. Evidence that the Ser192Tyr/Arg402Gln in cis Tyrosinase gene haplotype is a disease-causing allele in oculocutaneous albinism type 1B (OCA1B). NPJ Genom Med 2022; 7:2. [PMID: 35027574 PMCID: PMC8758782 DOI: 10.1038/s41525-021-00275-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/19/2021] [Indexed: 01/09/2023] Open
Abstract
Oculocutaneous albinism type 1 (OCA1) is caused by pathogenic variants in the TYR (tyrosinase) gene which encodes the critical and rate-limiting enzyme in melanin synthesis. It is the most common OCA subtype found in Caucasians, accounting for ~50% of cases worldwide. The apparent 'missing heritability' in OCA is well described, with ~25-30% of clinically diagnosed individuals lacking two clearly pathogenic variants. Here we undertook empowered genetic studies in an extensive multigenerational Amish family, alongside a review of previously published literature, a retrospective analysis of in-house datasets, and tyrosinase activity studies. Together this provides irrefutable evidence of the pathogenicity of two common TYR variants, p.(Ser192Tyr) and p.(Arg402Gln) when inherited in cis alongside a pathogenic TYR variant in trans. We also show that homozygosity for the p.(Ser192Tyr)/p.(Arg402Gln) TYR haplotype results in a very mild, but fully penetrant, albinism phenotype. Together these data underscore the importance of including the TYR p.(Ser192Tyr)/p.(Arg402Gln) in cis haplotype as a pathogenic allele causative of OCA, which would likely increase molecular diagnoses in this missing heritability albinism cohort by 25-50%.
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Affiliation(s)
- Siying Lin
- RILD Wellcome Wolfson Centre, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter, UK
| | - Aida Sanchez-Bretaño
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Joseph S Leslie
- RILD Wellcome Wolfson Centre, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter, UK
| | - Katie B Williams
- Center for Special Children, Vernon Memorial Healthcare, La Farge, WI, USA
| | - Helena Lee
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
- Southampton Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - N Simon Thomas
- Faculty of Medicine, University of Southampton, Southampton, UK
- Wessex Regional Genetics Laboratory, Salisbury District Hospital, Salisbury, UK
| | - Jonathan Callaway
- Faculty of Medicine, University of Southampton, Southampton, UK
- Wessex Regional Genetics Laboratory, Salisbury District Hospital, Salisbury, UK
| | - James Deline
- Center for Special Children, Vernon Memorial Healthcare, La Farge, WI, USA
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Diana Baralle
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Melanie A Schmitt
- University of Wisconsin School of Medicine and Public Health, Department of Ophthalmology & Visual Sciences, Madison, WI, USA
| | - Chelsea S Norman
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
- The Rosalind Franklin Institute, Rutherford Appleton Laboratories, Harwell Science and Innovation Campus, Didcot, UK
| | - Sheri Hammond
- Center for Special Children, Vernon Memorial Healthcare, La Farge, WI, USA
| | - Gaurav V Harlalka
- RILD Wellcome Wolfson Centre, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter, UK
- Rajarshi Shahu College of Pharmacy, Malvihir, Buldana, India
| | - Sarah Ennis
- Department of Human Genetics and Genomic Medicine, University of Southampton, Southampton, UK
| | - Harold E Cross
- Department of Ophthalmology, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Olivia Wenger
- New Leaf Clinic, PO Box 336, 16014 East Chestnut Street, Mount Eaton, OH, 44691, USA
- Department of Pediatrics, Akron Children's Hospital, 214 West Bowery Street, Akron, OH, 44308, USA
| | - Andrew H Crosby
- RILD Wellcome Wolfson Centre, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter, UK.
| | - Emma L Baple
- RILD Wellcome Wolfson Centre, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter, UK.
- Peninsula Clinical Genetics Service, Royal Devon & Exeter Hospital (Heavitree), Gladstone Road, Exeter, UK.
| | - Jay E Self
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.
- Southampton Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
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Karim S, Saharti S, Alganmi N, Mirza Z, Alfares A, Turkistany S, Al-Attas M, Noureldin H, Al Sakkaf K, Abusamra H, Al-Qahtani M, Abuzenadah A. Two Novel Homozygous HPS6 Mutations (Double Mutant) Identified by Whole-Exome Sequencing in a Saudi Consanguineous Family Suspected for Oculocutaneous Albinism. Life (Basel) 2021; 12:life12010014. [PMID: 35054407 PMCID: PMC8779141 DOI: 10.3390/life12010014] [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: 11/07/2021] [Revised: 12/11/2021] [Accepted: 12/13/2021] [Indexed: 11/28/2022] Open
Abstract
Background: Oculocutaneous albinism (OCA) is an autosomal recessive disorder of low or missing pigmentation in the eyes, hair, and skin. Multiple types of OCA, including Hermansky-Pudlak syndrome 6 (HPS6), are distinguished by their genetic cause and pigmentation pattern. HPS6 is characterized by OCA, nose bleeding due to platelet dysfunction, and lysosome storage defect. To date, 25 disease-associated mutations have been reported in the HPS6 gene. Methods: DNA was extracted from proband, and whole-exome sequencing (WES) was performed using the Illumina NovaSeq platform. Bioinformatic analysis was done with a custom-designed filter pipeline to detect the causative variant. We did Sanger sequencing to confirm the candidate variant and segregation analysis, and protein-based structural analysis to evaluate the functional impact of variants. Result: Proband-based WES identified two novel homozygous mutations in HPS6 (double mutation, c.1136C>A and c.1789delG) in an OCA suspect. Sanger sequencing confirmed the WES results. Although no platelet and/or lysosome storage defect was detected in the patient or family, an oculocutaneous albinism diagnosis was established based on the HPS6 mutations. Structural analysis revealed the transformation of abnormalities at protein level for both nonsense and frameshift mutations in HPS6. Conclusion: To the best of our knowledge, the double mutation in HPS6 (p.Ser379Ter and p.Ala597GlnfsTer16) represents novel pathogenic variants, not described previously, which we report for the first time in the Saudi family. In silico analyses showed a significant impact on protein structure. WES should be used to identify HPS6 and/or other disease-associated genetic variants in Saudi Arabia, particularly in consanguineous families.
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Affiliation(s)
- Sajjad Karim
- Center of Excellence in Genomic Medicine Research, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-Q.); (A.A.)
- Department of Medical Lab Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
- Correspondence: ; Tel.: +966-557581741
| | - Samah Saharti
- Department of Pathology, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Nofe Alganmi
- Computer Science Department, Faculty of Computing and Information Technology, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Zeenat Mirza
- Department of Medical Lab Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
- King Fahd Medical Research Center, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Ahmed Alfares
- Division of Genetics, Department of Pediatrics, King Abdulaziz Medical City, Riyadh 11426, Saudi Arabia;
| | - Shereen Turkistany
- Center of Innovation in Personalized Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Manal Al-Attas
- Roya Specialized Medical Laboratories, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-A.); (H.N.); (K.A.S.); (H.A.)
| | - Hend Noureldin
- Roya Specialized Medical Laboratories, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-A.); (H.N.); (K.A.S.); (H.A.)
| | - Khadega Al Sakkaf
- Roya Specialized Medical Laboratories, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-A.); (H.N.); (K.A.S.); (H.A.)
| | - Heba Abusamra
- Roya Specialized Medical Laboratories, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-A.); (H.N.); (K.A.S.); (H.A.)
| | - Mohammed Al-Qahtani
- Center of Excellence in Genomic Medicine Research, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-Q.); (A.A.)
| | - Adel Abuzenadah
- Center of Excellence in Genomic Medicine Research, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-Q.); (A.A.)
- Department of Medical Lab Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
- King Fahd Medical Research Center, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Roya Specialized Medical Laboratories, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (M.A.-A.); (H.N.); (K.A.S.); (H.A.)
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6
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Ma L, Zhu J, Wang J, Huang Y, Zhang J, Wang C, Zhou Y, Peng D. Genetic Analysis of 28 Chinese Families With Tyrosinase-Positive Oculocutaneous Albinism. Front Genet 2021; 12:715437. [PMID: 34707637 PMCID: PMC8544823 DOI: 10.3389/fgene.2021.715437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/30/2021] [Indexed: 11/28/2022] Open
Abstract
Background Tyrosinase-positive oculocutaneous albinism (OCA, type II, OCA2) is an autosomal recessive genetic disease in which the biosynthesis of melanin decreases in the skin, hair, and eyes. OCA2 disease is caused by mutations in OCA2 gene. The gene product plays a role in regulating the pH of melanosomes. Up to now, hundreds of OCA2 mutations have been reported and novel variants are still being discovered. Methods In this study, we reviewed the records of OCA2 patients who had conducted albinism genetic testing, and then analyzed the clinical and genetic information of 28 OCA2 patients who had been genetically diagnosed by using Sanger sequencing and next-generation sequencing. Results In this study, we reported 31 variants screened from 28 Chinese OCA2 families, and characterized the detailed molecular and clinical presentations. There were 12 novel variants among all detected variants, including 3 missense variants (p.G393V, p.T482A, and p.R720P), 4 frameshift variants (p.R53Gfs∗49, p.N279Kfs∗17, p.I469Lfs∗4, p.I655Nfs∗12), 2 splicing variants (c.1637-2A > G, c.1951 + 1G > C), 2 stopgain variants (p.L278X, p.W652X) and 1 insertion variants (p.P315LinsT). One potential cluster of missense variants was implicated indicating the important roles of the underlying domains in OCA2 pathogenesis. Conclusion Our results were beneficial for diagnosis and precision clinical management for OCA2-related disorder, and this study expanded the mutation spectrum of oculocutaneous albinism.
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Affiliation(s)
- Linya Ma
- Department of Medical Genetics, Changde First People's Hospital, Changde, China
| | - Jianjian Zhu
- Department of Medical Genetics, Changde First People's Hospital, Changde, China
| | - Jing Wang
- Changsha Kingmed Center for Clinical Laboratory, Changsha, China
| | - Yazhou Huang
- Department of Medical Genetics, Changde First People's Hospital, Changde, China
| | - Jibo Zhang
- Department of Medical Genetics, Changde First People's Hospital, Changde, China
| | - Chao Wang
- Department of Medical Genetics, Changde First People's Hospital, Changde, China
| | - Yuan Zhou
- Department of Medical Genetics, Changde First People's Hospital, Changde, China
| | - Dan Peng
- Department of Medical Genetics, Changde First People's Hospital, Changde, China.,Affiliated Hospital of Changde City, University of South China, Hengyang, China
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7
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Albinism: epidemiology, genetics, cutaneous characterization, psychosocial factors. An Bras Dermatol 2019; 94:503-520. [PMID: 31777350 PMCID: PMC6857599 DOI: 10.1016/j.abd.2019.09.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 09/09/2019] [Indexed: 11/20/2022] Open
Abstract
Oculocutaneous albinism is an autosomal recessive disease caused by the complete absence or decrease of melanin biosynthesis in melanocytes. Due to the reduction or absence of melanin, albinos are highly susceptible to the harmful effects of ultraviolet radiation and are at increased risk of actinic damage and skin cancer. In Brazil, as in other parts of the world, albinism remains a little known disorder, both in relation to epidemiological data and to phenotypic and genotypic variation. In several regions of the country, individuals with albinism have no access to resources or specialized medical care, and are often neglected and deprived of social inclusion. Brazil is a tropical country, with a high incidence of solar radiation during the year nationwide. Consequently, actinic damage and skin cancer occur early and have a high incidence in this population, often leading to premature death. Skin monitoring of these patients and immediate therapeutic interventions have a positive impact in reducing the morbidity and mortality associated with this condition. Health education is important to inform albinos and their families, the general population, educators, medical professionals, and public agencies about the particularities of this genetic condition. The aim of this article is to present a review of the epidemiological, clinical, genetic, and psychosocial characteristics of albinism, with a focus in skin changes caused by this rare pigmentation disorder.
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8
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Abstract
Albinism can be divided into oculocutaneous albinism (OCA) and ocular albinism (OA). In the differential diagnostics these can be distinguished from rarer syndromes with partial albinism, which are frequently associated with susceptibility to infections and neurological symptoms. The OCA is an autosomal recessive inherited disease of melanin biosynthesis, which leads to complete or partial loss of melanin in the skin, hair follicles and eyes. Of the seven currently known subtypes (OCA 1-7), four are well-characterized (OCA 1-4). These are based on gene mutations, which code for tyrosinase, a key enzyme in melanin synthesis and for further proteins. These play an important role in the catalytic activity of tyrosinase and the structure and function of melanosomes. In the presence of these subtypes, the clinical symptoms and the course of the disease show a pronounced variability, especially in the type and extent of pigmentation of the skin and hair as well as the severity of eye involvement, which makes the phenotypic classification difficult. Treatment priorities are a consistent protection from UV light for prophylaxis against skin cancer and regular preventive investigations. The ocular alterations typical for albinism necessitate timely diagnostics and care by institutions specialized in ophthalmology. Novel strategies for systemic treatment of subtypes of albinism are in preclinical testing. The OA without skin involvement shows X‑linked inheritance, is much rarer and is characterized by reduced pigmentation of the retina and iris, nystagmus and macular hypoplasia, sometimes with substantial loss of visual acuity. The typical ocular symptoms of OA can be manifested to a varying extent in all forms of OCA.
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Affiliation(s)
- A S Kubasch
- UniversitätsCentrum für Seltene Erkrankungen, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Dresden, Deutschland
| | - M Meurer
- Stiftung Hochschulmedizin Dresden, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Dresden, Deutschland.
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9
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Abstract
Human skin and hair color are visible traits that can vary dramatically within and across ethnic populations. The genetic makeup of these traits-including polymorphisms in the enzymes and signaling proteins involved in melanogenesis, and the vital role of ion transport mechanisms operating during the maturation and distribution of the melanosome-has provided new insights into the regulation of pigmentation. A large number of novel loci involved in the process have been recently discovered through four large-scale genome-wide association studies in Europeans, two large genetic studies of skin color in Africans, one study in Latin Americans, and functional testing in animal models. The responsible polymorphisms within these pigmentation genes appear at different population frequencies, can be used as ancestry-informative markers, and provide insight into the evolutionary selective forces that have acted to create this human diversity.
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Affiliation(s)
- William J Pavan
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Richard A Sturm
- Dermatology Research Centre, The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Queensland 4102, Australia;
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Wright CF, West B, Tuke M, Jones SE, Patel K, Laver TW, Beaumont RN, Tyrrell J, Wood AR, Frayling TM, Hattersley AT, Weedon MN. Assessing the Pathogenicity, Penetrance, and Expressivity of Putative Disease-Causing Variants in a Population Setting. Am J Hum Genet 2019; 104:275-286. [PMID: 30665703 PMCID: PMC6369448 DOI: 10.1016/j.ajhg.2018.12.015] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/20/2018] [Indexed: 12/15/2022] Open
Abstract
More than 100,000 genetic variants are classified as disease causing in public databases. However, the true penetrance of many of these rare alleles is uncertain and might be over-estimated by clinical ascertainment. Here, we use data from 379,768 UK Biobank (UKB) participants of European ancestry to assess the pathogenicity and penetrance of putatively clinically important rare variants. Although rare variants are harder to genotype accurately than common variants, we were able to classify as high quality 1,244 of 4,585 (27%) putatively clinically relevant rare (MAF < 1%) variants genotyped on the UKB microarray. We defined as "clinically relevant" variants that were classified as either pathogenic or likely pathogenic in ClinVar or are in genes known to cause two specific monogenic diseases: maturity-onset diabetes of the young (MODY) and severe developmental disorders (DDs). We assessed the penetrance and pathogenicity of these high-quality variants by testing their association with 401 clinically relevant traits. 27 of the variants were associated with a UKB trait, and we were able to refine the penetrance estimate for some of the variants. For example, the HNF4A c.340C>T (p.Arg114Trp) (GenBank: NM_175914.4) variant associated with diabetes is <10% penetrant by the time an individual is 40 years old. We also observed associations with relevant traits for heterozygous carriers of some rare recessive conditions, e.g., heterozygous carriers of the ERCC4 c.2395C>T (p.Arg799Trp) variant that causes Xeroderma pigmentosum were more susceptible to sunburn. Finally, we refute the previous disease association of RNF135 in developmental disorders. In conclusion, this study shows that very large population-based studies will help refine our understanding of the pathogenicity of rare genetic variants.
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Affiliation(s)
- Caroline F Wright
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK.
| | - Ben West
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Marcus Tuke
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Samuel E Jones
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Kashyap Patel
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Thomas W Laver
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Robin N Beaumont
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Jessica Tyrrell
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Andrew R Wood
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Timothy M Frayling
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Andrew T Hattersley
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Michael N Weedon
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Research, Innovation, Learning and Development building, Royal Devon & Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK.
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11
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Jung JH, Oh EH, Shin JH, Kim HS, Choi SY, Choi KD, Lee C, Choi JH. Identification of a novel GPR143 mutation in X-linked ocular albinism with marked intrafamilial phenotypic variability. J Genet 2018; 97:1479-1484. [PMID: 30555098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Ocular albinism type 1 (OA1) is an X-linked inherited disease characterized by impaired visual acuity, congenital nystagmus, foveal hypoplasia, hypopigmentation of iris and fundus. It is caused by mutations in the G protein-coupled receptor143 (GPR143) gene. The genetic characteristics of OA1 have not been well defined in Asians. In this study, six members from three consecutive generations of a Korean family with OA1 were enrolled. We performed whole-exome sequencing followed by validation and segregation analysis. Two affected patients underwent detailed ophthalmic examinations and eye movement recordings. Of the two affected males, the proband had all classical phenotypes of OA1, but the other showed isolated foveal hypoplasia without nystagmus. We identified a hemizygous missense (c.623C > A, p.Ala208Glu) mutation of GPR143 in affected males. This mutation was also present as heterozygous in two obligate female carriers, and was not found in unaffected members. Our data expands thespectrum of phenotypes and genotype in GPR143 in Asians, and highlights the phenotypic heterogeneity in OA1.
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Affiliation(s)
- Jae-Ho Jung
- Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea.
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12
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Identification of a novel GPR143 mutation in X-linked ocular albinism with marked intrafamilial phenotypic variability. J Genet 2018. [DOI: 10.1007/s12041-018-1024-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Arshad MW, Harlalka GV, Lin S, D'Atri I, Mehmood S, Shakil M, Hassan MJ, Chioza BA, Self JE, Ennis S, O'Gorman L, Norman C, Aman T, Ali SS, Kaul H, Baple EL, Crosby AH, Ullah MI, Shabbir MI. Mutations in TYR and OCA2 associated with oculocutaneous albinism in Pakistani families. Meta Gene 2018. [DOI: 10.1016/j.mgene.2018.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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14
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De Summa S, Guida M, Tommasi S, Strippoli S, Pellegrini C, Fargnoli MC, Pilato B, Natalicchio I, Guida G, Pinto R. Genetic profiling of a rare condition: co-occurrence of albinism and multiple primary melanoma in a Caucasian family. Oncotarget 2018; 8:29751-29759. [PMID: 27776349 PMCID: PMC5444700 DOI: 10.18632/oncotarget.12777] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/04/2016] [Indexed: 01/07/2023] Open
Abstract
Multiple primary melanoma (MPM) is a rare condition, whose genetic basis has not yet been clarified. Only 8-12% of MPM are due to germline mutations of CDKN2A. However, other genes (POT1, BRCA1/2, MC1R, MGMT) have been demonstrated to be involved in predisposition to this pathology. To our knowledge, this is the first family study based on two siblings with the rare coexistence of MPM and oculocutaneous albinism (OCA), an autosomal recessive disease characterized by the absence or decrease in pigmentation in the skin, hair, and eyes. In this study, we evaluated genes involved in melanoma predisposition (CDKN2A, CDK4, MC1R, MITF, POT1, RB1, MGMT, BRCA1, BRCA2), pathogenesis (BRAF, NRAS, PIK3CA, KIT, PTEN), skin/hair pigmentation (MC1R, MITF) and in immune pathways (CTLA4) to individuate alterations able to explain the rare onset of MPM and OCA in indexes and the transmission in their pedigree. From the analysis of the pedigree, we were able to identify a “protective” haplotype with respect to MPM, including MGMT p.I174V alteration. The second generation offspring is under strict follow up as some of them have a higher risk of developing MPM according to our model.
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Affiliation(s)
- Simona De Summa
- IRCCS Istituto Tumori "Giovanni Paolo II", Molecular Genetics Laboratory, Bari, Italy
| | - Michele Guida
- IRCCS Istituto Tumori "Giovanni Paolo II", Oncology Unit, Bari, Italy
| | - Stefania Tommasi
- IRCCS Istituto Tumori "Giovanni Paolo II", Molecular Genetics Laboratory, Bari, Italy
| | - Sabino Strippoli
- IRCCS Istituto Tumori "Giovanni Paolo II", Oncology Unit, Bari, Italy
| | - Cristina Pellegrini
- University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, L'Aquila, Italy
| | - Maria Concetta Fargnoli
- University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, L'Aquila, Italy
| | - Brunella Pilato
- IRCCS Istituto Tumori "Giovanni Paolo II", Molecular Genetics Laboratory, Bari, Italy
| | | | - Gabriella Guida
- University of Bari, Department of Medical Biochemistry, Bari, Italy
| | - Rosamaria Pinto
- IRCCS Istituto Tumori "Giovanni Paolo II", Molecular Genetics Laboratory, Bari, Italy
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Thomas AC, Heux P, Santos C, Arulvasan W, Solanky N, Carey ME, Gerrelli D, Kinsler VA, Etchevers HC. Widespread dynamic and pleiotropic expression of the melanocortin-1-receptor (MC1R) system is conserved across chick, mouse and human embryonic development. Birth Defects Res 2018; 110:443-455. [PMID: 29316344 PMCID: PMC6446732 DOI: 10.1002/bdr2.1183] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 11/17/2017] [Indexed: 12/28/2022]
Abstract
Background MC1R, a G‐protein coupled receptor with high affinity for alpha‐melanocyte stimulating hormone (αMSH), modulates pigment production in melanocytes from many species and is associated with human melanoma risk. MC1R mutations affecting human skin and hair color also have pleiotropic effects on the immune response and analgesia. Variants affecting human pigmentation in utero alter the congenital phenotype of both oculocutaneous albinism and congenital melanocytic naevi, and have a possible effect on birthweight. Methods and Results By in situ hybridization, RT‐PCR and immunohistochemistry, we show that MC1R is widely expressed during human, chick and mouse embryonic and fetal stages in many somatic tissues, particularly in the musculoskeletal and nervous systems, and conserved across evolution in these three amniotes. Its dynamic pattern differs from that of TUBB3, a gene overlapping the same locus in humans and encoding class III β‐tubulin. The αMSH peptide and the transcript for its precursor, pro‐opiomelanocortin (POMC), are similarly present in numerous extra‐cutaneous tissues. MC1R genotyping of variants p.(V60M) and p.(R151C) was undertaken for 867 healthy children from the Avon Longitudinal Study of Parent and Children (ALSPAC) cohort, and birthweight modeled using multiple logistic regression analysis. A significant positive association initially found between R151C and birth weight, independent of known birth weight modifiers, was not reproduced when combined with data from an independent genome‐wide association study of 6,459 additional members of the same cohort. Conclusions These data clearly show a new and hitherto unsuspected role for MC1R in noncutaneous solid tissues before birth.
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Affiliation(s)
- Anna C Thomas
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, United Kingdom
| | - Pauline Heux
- GMGF, Aix Marseille University, INSERM, UMR_S910, Marseille, France
| | - Chloe Santos
- Birth Defects Research Centre, UCL Institute of Child Health, London, United Kingdom
| | - Wisenave Arulvasan
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, United Kingdom
| | - Nita Solanky
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, United Kingdom
| | - Magalie E Carey
- GMGF, Aix Marseille University, INSERM, UMR_S910, Marseille, France
| | - Dianne Gerrelli
- Birth Defects Research Centre, UCL Institute of Child Health, London, United Kingdom
| | - Veronica A Kinsler
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, United Kingdom.,Department of Paediatric Dermatology, Great Ormond Street Hospital for Children, London, United Kingdom
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Polubothu S, Kinsler VA. The ethnic profile of patients with birthmarks reveals interaction of germline and postzygotic genetics. Br J Dermatol 2017; 176:1385-1387. [PMID: 28083870 PMCID: PMC5485042 DOI: 10.1111/bjd.15260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- S Polubothu
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, U.K.,Paediatric Dermatology, Great Ormond St Hospital for Children, London, U.K
| | - V A Kinsler
- Genetics and Genomic Medicine, UCL Institute of Child Health, London, U.K.,Paediatric Dermatology, Great Ormond St Hospital for Children, London, U.K
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Holmgaard H, Hansen EØ, Dong NPT, Dixen LB, Nielsen GAR, Poulsen JN, Gazerani P. Individuals with dark eyes and hair exhibit higher pain sensitivity. Somatosens Mot Res 2017; 34:21-26. [PMID: 28093011 DOI: 10.1080/08990220.2016.1276439] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Emerging evidence suggests that some phenotypic features, such as eye or hair colour, might predict pain. We investigated if light and dark eye and hair colour would influence pain in 60 healthy subjects divided in groups of 15 according to their eye-hair colour and gender. Pressure pain thresholds (PPTs), cold pressor test (CPT), and quality of the perceived pain were assessed. Findings indicated that dark pigmentation phenotype is more sensitive in response to CPT.
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Affiliation(s)
- Henrik Holmgaard
- a Department of Health Science and Technology , Aalborg University , Aalborg , Denmark
| | - Eva Ørsnæs Hansen
- a Department of Health Science and Technology , Aalborg University , Aalborg , Denmark
| | - Nhung Phuong Thi Dong
- a Department of Health Science and Technology , Aalborg University , Aalborg , Denmark
| | - Laila Brøns Dixen
- a Department of Health Science and Technology , Aalborg University , Aalborg , Denmark
| | | | | | - Parisa Gazerani
- a Department of Health Science and Technology , Aalborg University , Aalborg , Denmark
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18
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Schiffman JD, Breen M. Comparative oncology: what dogs and other species can teach us about humans with cancer. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0231. [PMID: 26056372 DOI: 10.1098/rstb.2014.0231] [Citation(s) in RCA: 232] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Over 1.66 million humans (approx. 500/100,000 population rate) and over 4.2 million dogs (approx. 5300/100,000 population rate) are diagnosed with cancer annually in the USA. The interdisciplinary field of comparative oncology offers a unique and strong opportunity to learn more about universal cancer risk and development through epidemiology, genetic and genomic investigations. Working across species, researchers from human and veterinary medicine can combine scientific findings to understand more quickly the origins of cancer and translate these findings to novel therapies to benefit both human and animals. This review begins with the genetic origins of canines and their advantage in cancer research. We next focus on recent findings in comparative oncology related to inherited, or genetic, risk for tumour development. We then detail the somatic, or genomic, changes within tumours and the similarities between species. The shared cancers between humans and dogs that we discuss include sarcoma (osteosarcoma, soft tissue sarcoma, histiocytic sarcoma, hemangiosarcoma), haematological malignancies (lymphoma, leukaemia), bladder cancer, intracranial neoplasms (meningioma, glioma) and melanoma. Tumour risk in other animal species is also briefly discussed. As the field of genomics advances, we predict that comparative oncology will continue to benefit both humans and the animals that live among us.
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Affiliation(s)
- Joshua D Schiffman
- Department of Pediatrics and Oncological Sciences, Primary Children's Hospital, Intermountain Healthcare, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Matthew Breen
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, Center for Comparative Medicine and Translational Research, Center for Human Health and the Environment, Cancer Genetics, UNC Lineberger Comprehensive Cancer Center, North Carolina State University, Raleigh, NC, USA
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20
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Oculocutaneous Albinism and Squamous Cell Carcinoma of the Skin of the Head and Neck in Sub-Saharan Africa. J Skin Cancer 2015; 2015:167847. [PMID: 26347819 PMCID: PMC4549604 DOI: 10.1155/2015/167847] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 07/30/2015] [Indexed: 11/18/2022] Open
Abstract
Oculocutaneous albinism which is characterised by impaired melanin biosynthesis is the most common inherited pigmentary disorder of the skin and it is common among Blacks in sub-Saharan Africa. All albinos are at great risk of developing squamous cell carcinoma of sun-exposed skin, and Black albinos in sub-Saharan Africa are at about a 1000-fold higher risk of developing squamous cell carcinoma of the skin than the general population. In Black albinos, skin carcinoma tends to run an aggressive course and is likely to recur after treatment, very probably because the aetiology and predisposing factors have not changed. Prevention or reduction of occurrence of squamous cell carcinoma of the skin in Black albinos might be achieved through educating the population to increase awareness of the harmful effects of exposure to sunlight and at the same time making available effective screening programs for early detection of premalignant and malignant skin lesions in schools and communities and for early treatment.
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21
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Lemer S, Saulnier D, Gueguen Y, Planes S. Identification of genes associated with shell color in the black-lipped pearl oyster, Pinctada margaritifera. BMC Genomics 2015; 16:568. [PMID: 26231360 PMCID: PMC4521380 DOI: 10.1186/s12864-015-1776-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Accepted: 07/14/2015] [Indexed: 11/13/2022] Open
Abstract
Background Color polymorphism in the nacre of pteriomorphian bivalves is of great interest for the pearl culture industry. The nacreous layer of the Polynesian black-lipped pearl oyster Pinctada margaritifera exhibits a large array of color variation among individuals including reflections of blue, green, yellow and pink in all possible gradients. Although the heritability of nacre color variation patterns has been demonstrated by experimental crossing, little is known about the genes involved in these patterns. In this study, we identify a set of genes differentially expressed among extreme color phenotypes of P. margaritifera using a suppressive and subtractive hybridization (SSH) method comparing black phenotypes with full and half albino individuals. Results Out of the 358 and 346 expressed sequence tags (ESTs) obtained by conducting two SSH libraries respectively, the expression patterns of 37 genes were tested with a real-time quantitative PCR (RT-qPCR) approach by pooling five individuals of each phenotype. The expression of 11 genes was subsequently estimated for each individual in order to detect inter-individual variation. Our results suggest that the color of the nacre is partially under the influence of genes involved in the biomineralization of the calcitic layer. A few genes involved in the formation of the aragonite tablets of the nacre layer and in the biosynthesis chain of melanin also showed differential expression patterns. Finally, high variability in gene expression levels were observed within the black phenotypes. Conclusions Our results revealed that three main genetic processes were involved in color polymorphisms: the biomineralization of the nacreous and calcitic layers and the synthesis of pigments such as melanin, suggesting that color polymorphism takes place at different levels in the shell structure. The high variability of gene expression found within black phenotypes suggests that the present work should serve as a basis for future studies exploring more thoroughly the expression patterns of candidate genes within black phenotypes with different dominant iridescent colors. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1776-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sarah Lemer
- Laboratoire d'Excellence "CORAIL", USR 3278 CNRS-CRIOBE- EPHE, Perpignan, France, Papetoai, Moorea, French Polynesia. .,Present address: Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA.
| | - Denis Saulnier
- Ifremer, UMR 241 EIO, Laboratoire d'Excellence "CORAIL", BP 7004, 98719, Taravao, Tahiti, French Polynesia.
| | - Yannick Gueguen
- Ifremer, UMR 241 EIO, Laboratoire d'Excellence "CORAIL", BP 7004, 98719, Taravao, Tahiti, French Polynesia. .,Present address: Ifremer, UMR 5244 IHPE, UPVD, CNRS, Université de Montpellier, CC 80, F-34095, Montpellier, France.
| | - Serge Planes
- Laboratoire d'Excellence "CORAIL", USR 3278 CNRS-CRIOBE- EPHE, Perpignan, France, Papetoai, Moorea, French Polynesia.
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Bellono NW, Escobar IE, Lefkovith AJ, Marks MS, Oancea E. An intracellular anion channel critical for pigmentation. eLife 2014; 3:e04543. [PMID: 25513726 PMCID: PMC4270065 DOI: 10.7554/elife.04543] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/07/2014] [Indexed: 12/28/2022] Open
Abstract
Intracellular ion channels are essential regulators of organellar and cellular function, yet the molecular identity and physiological role of many of these channels remains elusive. In particular, no ion channel has been characterized in melanosomes, organelles that produce and store the major mammalian pigment melanin. Defects in melanosome function cause albinism, characterized by vision and pigmentation deficits, impaired retinal development, and increased susceptibility to skin and eye cancers. The most common form of albinism is caused by mutations in oculocutaneous albinism II (OCA2), a melanosome-specific transmembrane protein with unknown function. Here we used direct patch-clamp of skin and eye melanosomes to identify a novel chloride-selective anion conductance mediated by OCA2 and required for melanin production. Expression of OCA2 increases organelle pH, suggesting that the chloride channel might regulate melanin synthesis by modulating melanosome pH. Thus, a melanosomal anion channel that requires OCA2 is essential for skin and eye pigmentation.
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Affiliation(s)
- Nicholas W Bellono
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Iliana E Escobar
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Ariel J Lefkovith
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, United States
| | - Michael S Marks
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, United States
| | - Elena Oancea
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
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24
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Kraft S, Granter SR. Molecular pathology of skin neoplasms of the head and neck. Arch Pathol Lab Med 2014; 138:759-87. [PMID: 24878016 DOI: 10.5858/arpa.2013-0157-ra] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region. OBJECTIVE To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations. DATA SOURCES Literature review. CONCLUSIONS Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.
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Affiliation(s)
- Stefan Kraft
- From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Dr Kraft); and the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts (Dr Granter)
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Sengupta M, Sarkar D, Mondal M, Samanta S, Sil A, Ray K. Analysis of MC1R variants in Indian oculocutaneous albinism patients: highlighting the risk of skin cancer among albinos. J Genet 2014; 92:305-8. [PMID: 23970088 DOI: 10.1007/s12041-013-0250-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Mainak Sengupta
- Molecular and Human Genetics Division, Council of Scientific and Industrial Research - Indian Institute of Chemical Biology, Kolkata 700 032, India
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Rooryck C, Morice F, Lacombe D, Taieb A, Arveiler B. Genetic basis of oculocutaneous albinism. ACTA ACUST UNITED AC 2014. [DOI: 10.1586/edm.09.53] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Al-Araimi M, Pal B, Poulter JA, van Genderen MM, Carr I, Cudrnak T, Brown L, Sheridan E, Mohamed MD, Bradbury J, Ali M, Inglehearn CF, Toomes C. A new recessively inherited disorder composed of foveal hypoplasia, optic nerve decussation defects and anterior segment dysgenesis maps to chromosome 16q23.3-24.1. Mol Vis 2013; 19:2165-72. [PMID: 24194637 PMCID: PMC3816992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/29/2013] [Indexed: 11/06/2022] Open
Abstract
PURPOSE We have previously described two families with unique phenotypes involving foveal hypoplasia. The first family (F1) presented with foveal hypoplasia and anterior segment dysgenesis, and the second family (F2) presented with foveal hypoplasia and chiasmal misrouting in the absence of albinism. A genome-wide linkage search in family F1 identified a 6.5 Mb locus for this disorder on chromosome 16q23.2-24.1. The aim of this study was to determine if both families have the same disorder and to see if family F2 is also linked to the 16q locus. METHODS Family members underwent routine clinical examination. Linkage was determined by genotyping microsatellite makers and calculating logarithm of the odds (LOD) scores. Locus refinement was undertaken with single nucleotide polymorphism (SNP) microarray analysis. RESULTS The identification of chiasmal misrouting in family F1 and anterior segment abnormalities in family F2 suggested that the families have the same clinical phenotype. This was confirmed when linkage analysis showed that family F2 also mapped to the 16q locus. The single nucleotide polymorphism microarray analysis excluded a shared founder haplotype between the families and refined the locus to 3.1 Mb. CONCLUSIONS We report a new recessively inherited syndrome consisting of foveal hypoplasia, optic nerve decussation defects and anterior segment dysgenesis, which we have abbreviated to FHONDA syndrome. The gene mutated in this disorder lies within a 3.1 Mb interval containing 33 genes on chromosome 16q23.3-24.1 (chr16:83639061 - 86716445, hg19).
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Affiliation(s)
- Musallam Al-Araimi
- Section of Ophthalmology and Neuroscience, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
| | - Bishwanath Pal
- Section of Ophthalmology and Neuroscience, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
| | - James A. Poulter
- Section of Ophthalmology and Neuroscience, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
| | | | - Ian Carr
- Section of Translational Medicine, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
| | - Tomas Cudrnak
- Department of Ophthalmology, Bradford Royal Infirmary, Bradford, UK
| | - Lawrence Brown
- Department of Ophthalmology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Eamonn Sheridan
- Section of Genetics, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK,Department of Clinical Genetics, St James’s University Hospital, Leeds, UK
| | - Moin D. Mohamed
- Section of Ophthalmology and Neuroscience, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
| | - John Bradbury
- Department of Ophthalmology, Bradford Royal Infirmary, Bradford, UK
| | - Manir Ali
- Section of Ophthalmology and Neuroscience, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
| | - Chris F. Inglehearn
- Section of Ophthalmology and Neuroscience, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
| | - Carmel Toomes
- Section of Ophthalmology and Neuroscience, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK
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Hawkes JE, Cassidy PB, Manga P, Boissy RE, Goldgar D, Cannon-Albright L, Florell SR, Leachman SA. Report of a novel OCA2 gene mutation and an investigation of OCA2 variants on melanoma risk in a familial melanoma pedigree. J Dermatol Sci 2013; 69:30-7. [PMID: 23103111 PMCID: PMC4775076 DOI: 10.1016/j.jdermsci.2012.09.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 08/26/2012] [Accepted: 09/27/2012] [Indexed: 11/21/2022]
Abstract
BACKGROUND Oculocutaneous albinism type 2 (OCA2) is caused by mutations of the OCA2 gene. Individuals affected by OCA2 as well as other types of albinism are at a significantly increased risk for sun-induced skin-cancers, including malignant melanoma (MM). OBJECTIVE To identify the molecular etiology of oculocutaneous albinism in a previously uncharacterized melanoma pedigree and to investigate the relationship between two OCA2 variants and melanoma predisposition in this pedigree. METHODS DNA and RNA were isolated from the peripheral blood of seven patients in a familial melanoma pedigree. Electron microscopy was performed on the individual with clinical oculocutaneous albinism. OCA2, TYRP1, MC1R, CDKN2A/p16, CDKN2A/p19ARF, and CDK4 genes were sequenced in affected individuals. The relationship between OCA2 variants and melanoma was assessed using a pedigree likelihood-based method. RESULTS The proband was determined to be an OCA2 compound heterozygous mutation carrier with a previously reported conservative missense mutation (V443I) and a novel non-conservative missense mutation (L734R). The pedigree contained individuals diagnosed with both cutaneous and iris melanoma. Based on co-segregation analysis, the odds of these OCA2 variants being high penetrance loci for melanoma was: 1.3-to-1 if we include the iris melanoma as affected and 6.5-to-1 if we only consider cutaneous melanoma as affected. CONCLUSION The discovery of this novel OCA2 variant adds to the body of evidence on the detrimental effects of OCA2 gene mutations on pigmentation, supports existing GWAS data on the relevance of the OCA2 gene in melanoma predisposition, and may ultimately assist in the development of targeted molecular therapies in the treatment of OCA and melanoma.
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Affiliation(s)
- Jason E. Hawkes
- Huntsman Cancer Institute and Department of Dermatology, University of Utah Health Sciences Center, Salt Lake City, UT, USA
| | - Pamela B. Cassidy
- Huntsman Cancer Institute and Department of Dermatology, University of Utah Health Sciences Center, Salt Lake City, UT, USA
- Department of Medicinal Chemistry L.S. Skagg's Pharmacy, University of Utah Health Sciences Center, Salt Lake City, UT, USA
| | - Prashiela Manga
- Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, NY, USA
| | - Raymond E. Boissy
- Department of Dermatology, University of Cincinnati, Cincinnati, OH, USA
| | - David Goldgar
- Huntsman Cancer Institute and Department of Dermatology, University of Utah Health Sciences Center, Salt Lake City, UT, USA
| | - Lisa Cannon-Albright
- Department of Biomedical Informatics, Huntsman Cancer Institute, Salt Lake City, UT, USA
| | - Scott R. Florell
- Huntsman Cancer Institute and Department of Dermatology, University of Utah Health Sciences Center, Salt Lake City, UT, USA
| | - Sancy A. Leachman
- Huntsman Cancer Institute and Department of Dermatology, University of Utah Health Sciences Center, Salt Lake City, UT, USA
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Saleha SB, Ajaml M, Jamil M, Nasir M, Hameed A. MC1R gene mutation and its association with oculocutaneous albinism type (OCA) phenotype in a consanguineous Pakistani family. J Dermatol Sci 2012; 70:68-70. [PMID: 23312576 DOI: 10.1016/j.jdermsci.2012.11.591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 11/08/2012] [Accepted: 11/29/2012] [Indexed: 01/10/2023]
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Yu W, Wang C, Xin Q, Li S, Feng Y, Peng X, Gong Y. Non-synonymous SNPs inMC1Rgene are associated with the extended black variant in domestic ducks (Anas platyrhynchos). Anim Genet 2012; 44:214-6. [DOI: 10.1111/j.1365-2052.2012.02377.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Wenhua Yu
- Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology, Huazhong Agricultural University; Wuhan Hubei 430070, P.R. China
| | - Cui Wang
- Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology, Huazhong Agricultural University; Wuhan Hubei 430070, P.R. China
| | - Qingwu Xin
- Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology, Huazhong Agricultural University; Wuhan Hubei 430070, P.R. China
| | - Shijun Li
- Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology, Huazhong Agricultural University; Wuhan Hubei 430070, P.R. China
| | - Yanping Feng
- Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology, Huazhong Agricultural University; Wuhan Hubei 430070, P.R. China
| | - Xiuli Peng
- Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology, Huazhong Agricultural University; Wuhan Hubei 430070, P.R. China
| | - Yanzhang Gong
- Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education; College of Animal Science and Technology, Huazhong Agricultural University; Wuhan Hubei 430070, P.R. China
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Kinsler VA, Abu-Amero S, Budd P, Jackson IJ, Ring SM, Northstone K, Atherton DJ, Bulstrode NW, Stanier P, Hennekam RC, Sebire NJ, Moore GE, Healy E. Germline melanocortin-1-receptor genotype is associated with severity of cutaneous phenotype in congenital melanocytic nevi: a role for MC1R in human fetal development. J Invest Dermatol 2012; 132:2026-32. [PMID: 22572819 PMCID: PMC3398254 DOI: 10.1038/jid.2012.95] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Congenital melanocytic nevi (CMN) are pigmented birthmarks that affect up to 80% of the skin surface area. The increased frequency of CMN in families of severely affected individuals is suggestive of a predisposing germline genotype. We noted a high prevalence of red hair in affected families, and considered a role for MC1R in this condition. A cohort of 166 CMN subjects underwent pigmentary phenotyping, with MC1R genotyping in 113. Results were compared with a local control group of 60 unrelated children and with 300 UK children without CMN. CMN subjects had higher prevalences of red hair and a red-haired parent than local controls and had a higher rate of compound heterozygosity and homozygosity for MC1R variants. The presence of a V92M or R allele (D84E, R151C, R160W, D294H) was associated with increasing size of the CMN, implying a growth-promoting effect of these alleles. Unexpectedly, the V92M and R151C alleles were also strongly associated with birth weight in the CMN cohort, a finding confirmed in the control group. The effect of germline MC1R genotype on development and severity of CMN led us to investigate potential broader effects on growth, revealing a role for MC1R in normal fetal development.
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Affiliation(s)
- Veronica A Kinsler
- Department of Paediatric Dermatology, Great Ormond Street Hospital for Children, London, UK
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Ito S, Wakamatsu K. Diversity of human hair pigmentation as studied by chemical analysis of eumelanin and pheomelanin. J Eur Acad Dermatol Venereol 2012; 25:1369-80. [PMID: 22077870 DOI: 10.1111/j.1468-3083.2011.04278.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Hair colour is one of the most conspicuous phenotypes in humans, ranging from black, brown, blond to red. This diversity arises mostly from the quantity and ratio of the black-dark brown eumelanin and the reddish-brown pheomelanin. To study the chemical basis underlying the diversity of hair colour, we have developed several chemical methods to quantify those two pigments. Alkaline H(2) O(2) oxidation affords pyrrole-2,3,5-tricarboxylic acid (PTCA) as a eumelanin marker and thiazole-2,4,5-tricarboxylic acid (TTCA) as a pheomelanin marker. Pheomelanin can also be analysed as 4-amino-3-hydroxyphenylalanine (4-AHP) after hydroiodic acid hydrolysis. Using those methods, we evaluated the contents of eumelanin and pheomelanin (the 'chemical' phenotype) in human hairs of black, dark brown, brown, light brown, blond and red colour (the 'visual' phenotype). Eumelanin contents decrease in that order, with a trace but constant level of pheomelanin, except for red hair which contains about equal levels of pheomelanin and eumelanin. Thus, the chemical phenotype correlates well with the visual phenotype. The genotype of melanocortin-1 receptor (MC1R), a gene regulating the red hair phenotype, is predictive of hair melanin expressed as the log value of eumelanin to pheomelanin ratio, with a dosage effect evident. Hair melanin contents were also analysed in patients with various hypopigmentary disorders including Hermansky-Pudlak syndrome, Menkes disease, proopiomelanocortin deficiency, cystinosis, malnutrition and trace metal deficiency. The chemical phenotype helped evaluate the precise effects of each disease on pigmentation. In studies of human hair, the chemical phenotype will find more and more application as an objective measure of pigmentation.
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Affiliation(s)
- S Ito
- Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi, Japan.
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Low D, Chen KS. UBE3A regulates MC1R expression: a link to hypopigmentation in Angelman syndrome. Pigment Cell Melanoma Res 2011; 24:944-52. [DOI: 10.1111/j.1755-148x.2011.00884.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Ito S, Wakamatsu K. Human hair melanins: what we have learned and have not learned from mouse coat color pigmentation. Pigment Cell Melanoma Res 2011; 24:63-74. [PMID: 20726950 DOI: 10.1111/j.1755-148x.2010.00755.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hair pigmentation is one of the most conspicuous phenotypes in humans. Melanocytes produce two distinct types of melanin pigment: brown to black, indolic eumelanin and yellow to reddish brown, sulfur-containing pheomelanin. Biochemically, the precursor tyrosine and the key enzyme tyrosinase and the tyrosinase-related proteins are involved in eumelanogenesis, while only the additional presence of cysteine is necessary for pheomelanogenesis. Other important proteins involved in melanogenesis include P protein, MATP protein, α-MSH, agouti signaling protein (ASIP), MC1R (the receptor for MSH and ASIP), and SLC7A11, a cystine transporter. Many studies have examined the effects of loss-of-function mutations of those proteins on mouse coat color pigmentation. In contrast, much less is known regarding the effects of mutations of the corresponding proteins on human hair pigmentation except for MC1R polymorphisms that lead to pheomelanogenesis. This perspective will discuss what we have/have not learned from mouse coat color pigmentation, with special emphasis on the significant roles of pH and the level of cysteine in melanosomes in controlling melanogenesis. Based on these data, a hypothesis is proposed to explain the diversity of human hair pigmentation.
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Affiliation(s)
- Shosuke Ito
- Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi, Japan.
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Preising MN, Forster H, Gonser M, Lorenz B. Screening of TYR, OCA2, GPR143, and MC1R in patients with congenital nystagmus, macular hypoplasia, and fundus hypopigmentation indicating albinism. Mol Vis 2011; 17:939-48. [PMID: 21541274 PMCID: PMC3084229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Accepted: 04/05/2011] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND A broad spectrum of pigmentation of the skin and hair is found among patients diagnosed with ocular albinism (OA) and oculocutaneous albinism (OCA). Even though complexion is variable, three ocular features, i.e., hypopigmentation of the fundus, hypoplasia of the macula, and nystagmus, are classical pathological findings in these patients. We screened 172 index patients with a clinical diagnosis of OA or OCA based on the classical findings, to evaluate the frequency of sequence variants in tyrosinase (TYR), P-gene, P-protein (OCA2), and the G-protein-coupled receptor 143 gene, OA1 (GPR143). In addition, we investigated the association of sequence variants in the melanocortin receptor 1 gene (MC1R) and OCA2. METHODS Pigmentation of the hair, skin, iris, and fundus were included in the evaluation of OCA and OA. Male OA patients showing X-linked inheritance were screened for GPR143. Females showing OA without family history were regarded as representing autosomal recessive OA (OA3). Direct sequencing was applied to PCR products showing aberrant single-strand conformation polymorphism-banding patterns. RESULTS Fifty-seven male index patients were screened for OA. We identified 16 potentially pathogenic sequence variations in GPR143 (10 novel) in 22 males. In TYR, we identified 23 (7 novel), and in OCA2 28 (11 novel) possibly pathogenic variants. Variants on both alleles were identified in TYR or OCA2 in 29/79 OCA patients and 14/71 OA patients. Sequence changes in TYR were identified almost exclusively in OCA patients, while sequence changes in OCA2 occurred in OCA and OA patients. MC1R sequencing was performed in 47 patients carrying mutations in OCA2 and revealed MC1R mutations in 42 of them. CONCLUSIONS TYR gene mutations have a more severe effect on pigmentation than mutations in OCA2 and the GPR143 gene. Nevertheless, mutations in these genes affect the development of visual function either directly or by interaction with other genes like MC1R, which can be deduced from a frequent association of MC1R variants with p.R305W or p.R419Q in OCA2.
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Affiliation(s)
- Markus N. Preising
- Department of Paediatric Ophthalmology, Strabismology, and Ophthalmogenetics, University Medical Centre, University of Regensburg, Regensburg, Germany,Department of Ophthalmology, Justus-Liebig-University Giessen, Universitaetsklinikum Giessen and Marburg GmbH, Giessen Campus, Giessen, Germany
| | - Hedwig Forster
- Department of Paediatric Ophthalmology, Strabismology, and Ophthalmogenetics, University Medical Centre, University of Regensburg, Regensburg, Germany
| | - Miriam Gonser
- Department of Paediatric Ophthalmology, Strabismology, and Ophthalmogenetics, University Medical Centre, University of Regensburg, Regensburg, Germany
| | - Birgit Lorenz
- Department of Paediatric Ophthalmology, Strabismology, and Ophthalmogenetics, University Medical Centre, University of Regensburg, Regensburg, Germany,Department of Ophthalmology, Justus-Liebig-University Giessen, Universitaetsklinikum Giessen and Marburg GmbH, Giessen Campus, Giessen, Germany
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Gargiulo A, Testa F, Rossi S, Di Iorio V, Fecarotta S, de Berardinis T, Iovine A, Magli A, Signorini S, Fazzi E, Galantuomo MS, Fossarello M, Montefusco S, Ciccodicola A, Neri A, Macaluso C, Simonelli F, Surace EM. Molecular and clinical characterization of albinism in a large cohort of Italian patients. Invest Ophthalmol Vis Sci 2011; 52:1281-9. [PMID: 20861488 DOI: 10.1167/iovs.10-6091] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The purpose of this study was to identify the molecular basis of albinism in a large cohort of Italian patients showing typical ocular landmarks of the disease and to provide a full characterization of the clinical ophthalmic manifestations. METHODS DNA samples from 45 patients with ocular manifestations of albinism were analyzed by direct sequencing analysis of five genes responsible for albinism: TYR, P, TYRP1, SLC45A2 (MATP), and OA1. All patients studied showed a variable degree of skin and hair hypopigmentation. Eighteen patients with distinct mutations in each gene associated with OCA were evaluated by detailed ophthalmic analysis, optical coherence tomography (OCT), and fundus autofluorescence. RESULTS Disease-causing mutations were identified in more than 95% of analyzed patients with OCA (28/45 [62.2%] cases with two or more mutations; 15/45 [33.3%] cases with one mutation). Thirty-five different mutant alleles were identified of which 15 were novel. Mutations in TYR were the most frequent (73.3%), whereas mutations in P occurred more rarely (13.3%) than previously reported. Novel mutations were also identified in rare loci such as TYRP1 and MATP. Mutations in the OA1 gene were not detected. Clinical assessment revealed that patients with iris and macular pigmentation had significantly higher visual acuity than did severe hypopigmented phenotypes. CONCLUSIONS TYR gene mutations represent a relevant cause of oculocutaneous albinism in Italy, whereas mutations in P present a lower frequency than that found in other populations. Clinical analysis revealed that the severity of the ocular manifestations depends on the degree of retinal pigmentation.
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Abstract
Albinism is a group of disorders characterized principally by its ophthalmic features with or without systemic manifestations. Persons with albinism manifest a wide variety of phenotypes and limited number of genotypes. Modern molecular genetics has encouraged a new classification and understanding of the subtypes of these disorders. In addition to the ocular and systemic manifestations, ophthalmologists must be familiar with the specific visual needs and psychological challenges of these individuals as well as those of their families.
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Affiliation(s)
- Alex V Levin
- Wills Eye Institute, Pediatric Ophthalmology and Ocular Genetics, Philadelphia, Pennsylvania 19107, USA.
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Kondo T, Hearing VJ. Update on the regulation of mammalian melanocyte function and skin pigmentation. EXPERT REVIEW OF DERMATOLOGY 2011; 6:97-108. [PMID: 21572549 PMCID: PMC3093193 DOI: 10.1586/edm.10.70] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Melanogenesis is the unique process of producing pigmented biopolymers that are sequestered within melanosomes, which provides color to the skin, hair and eyes of animals and, in the case of human skin, also protects the underlying tissues from UV damage. We review the current understanding of melanogenesis, focusing on factors important to the biochemistry of pigment synthesis, the biogenesis of melanosomes, signaling pathways and factors that regulate melanogenesis, intramelanosomal pH, transport and transfer of melanosomes, and pigmentary disorders related to the dysfunction of melanosome-related proteins. Although it has been known for some time that many of the factors that affect melanogenesis are derived from keratinocytes, fibroblasts, endothelial cells, hormones, inflammatory cells and nerves, a number of new factors that are involved in that regulation have recently been reported, such as factors that regulate melanosome pH and ion transport.
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Affiliation(s)
- Taisuke Kondo
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Vincent J Hearing
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Hirobe T, Ito S, Wakamatsu K. The mouse pink-eyed dilution allele of the P-gene greatly inhibits eumelanin but not pheomelanin synthesis. Pigment Cell Melanoma Res 2010; 24:241-6. [PMID: 21232027 DOI: 10.1111/j.1755-148x.2010.00783.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The mouse pink-eyed dilution (p) locus is known to control eumelanin synthesis, melanosome morphology, and tyrosinase activity in melanocytes. However, it has not been fully determined whether the mutant allele, p affects pheomelanin synthesis. Effects of the p allele on eumelanin and phemelanin synthesis were investigated by chemical analysis of dorsal hairs of 5-week-old mice obtained from the F(2) generations (black, pink-eyed black, recessive yellow, pink-eyed recessive yellow, agouti, and pink-eyed agouti) between C57BL/10JHir (B10)-congenic pink-eyed black mice (B10-p/p) and recessive yellow (B10-Mc1r(e)/Mc1r(e)) or agouti (B10-A/A) mice. The eumelanin content was dramatically (>20-fold) decreased in pink-eyed black and pink-eyed agouti mice, whereas the pheomelanin content did not decrease in pink-eyed black, pink-eyed recessive yellow, or pink-eyed agouti mice compared to the corresponding P/- mice. These results suggest that the pink-eyed dilution allele greatly inhibits eumelanin synthesis, but not pheomelanin synthesis.
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Affiliation(s)
- Tomohisa Hirobe
- Radiation Effect Mechanisms Research Group, National Institute of Radiological Sciences, Anagawa, Inage-ku, Chiba, Japan.
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40
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Ito S, Wakamatsu K. Human hair melanins: what we have learned and have not learned from mouse coat color pigmentation. Pigment Cell Melanoma Res 2010. [DOI: 10.1111/j.1755-1471.2010.00755.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Inheritance of a novel mutated allele of the OCA2 gene associated with high incidence of oculocutaneous albinism in a Polynesian community. J Hum Genet 2009; 55:103-11. [PMID: 20019752 DOI: 10.1038/jhg.2009.130] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Oculocutaneous albinism type 2 (OCA2) is a human autosomal-recessive hypopigmentation disorder associated with pathological mutations of the OCA2 gene. In this study, we investigated a form of OCA in a Polynesian population with an observed phenotype characterized by fair skin, some brown nevi present in the sun-exposed areas and green or blue eyes. Hair presented with a unique red coloration since birth, with tones ranging across individuals from Yellow-Red to Brown-Red, or Auburn. We genetically screened for mutations in the OCA2 and MC1R genes as their products have previously been shown to be associated with red hair/fair skin and OCA2. The SLC45A2 gene was also screened to identify any possible relation to skin color variation. We have identified a novel missense substitution in the OCA2 gene (Gly775Asp) responsible for OCA2 in individuals of Polynesian heritage from Tuvalu. The estimated incidence of this form of OCA2 in the primary study community is believed to occur at one of the highest recorded rates of albinism at approximately 1 per 669 individuals. In addition, we have analyzed four unrelated individuals with albinism who have Polynesian heritage from three other separate communities and found they carry the same OCA2 mutation. We also analyzed an out-group comprising three unrelated individuals with albinism of Melanesian ancestries from two separate communities, one Australian Aboriginal and three Australian Caucasians, and did not detect this mutation. We hypothesize that this mutation may be Polynesian specific and that it originated from a common founder.
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Mengel-From J, Børsting C, Sanchez JJ, Eiberg H, Morling N. Determination of cis/trans phase of variations in the MC1R gene with allele-specific PCR and single base extension. Electrophoresis 2009; 29:4780-7. [PMID: 19016241 DOI: 10.1002/elps.200800107] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The MC1R gene encodes a protein with key regulatory functions in the melanin synthesis. A multiplex PCR and a multiplex single base extension protocol were established for genotyping six exonic MC1R variations highly penetrant for red hair (R), four exonic MC1R variations weakly penetrant for red hair (r), two frameshift variations highly penetrant for red hair (R) and three variations in the promoter region. We genotyped 600 individuals from Denmark using either CE or MALDI-TOF MS as the detection platform. A total of 62 individuals were genotyped R/R and among the 62 individuals, 57 had red hair and five had blond hair colour. Two different R alleles may be located in cis (RR/-) position or trans (R/R) position, and the phenotype associated with RR/- and R/R may be different. Two allele-specific PCRs were established with primers targeting the -G445A variation in the MC1R promoter and the allele-specific PCR products were used in the multiplex single base extension assay. In all 62 individuals, the MC1R variants were situated in trans position. Another 18 individuals with red hair colour were either genotyped R/- or R/r, suggesting that other genes influence hair colour.
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Affiliation(s)
- Jonas Mengel-From
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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Abstract
A diverse group of animals, including members of most major phyla, have adapted to life in the perpetual darkness of caves. These animals are united by the convergence of two regressive phenotypes, loss of eyes and pigmentation. The mechanisms of regressive evolution are poorly understood. The teleost Astyanax mexicanus is of special significance in studies of regressive evolution in cave animals. This species includes an ancestral surface dwelling form and many con-specific cave-dwelling forms, some of which have evolved their recessive phenotypes independently. Recent advances in Astyanax development and genetics have provided new information about how eyes and pigment are lost during cavefish evolution; namely, they have revealed some of the molecular and cellular mechanisms involved in trait modification, the number and identity of the underlying genes and mutations, the molecular basis of parallel evolution, and the evolutionary forces driving adaptation to the cave environment.
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Affiliation(s)
- William R Jeffery
- Department of Biology, University of Maryland, College Park, Maryland 20742, USA.
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Chiang PW, Fulton AB, Spector E, Hisama FM. Synergistic interaction of theOCA2andOCA3genes in a family. Am J Med Genet A 2008; 146A:2427-30. [DOI: 10.1002/ajmg.a.32453] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Analysis of cultured human melanocytes based on polymorphisms within the SLC45A2/MATP, SLC24A5/NCKX5, and OCA2/P loci. J Invest Dermatol 2008; 129:392-405. [PMID: 18650849 DOI: 10.1038/jid.2008.211] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Single nucleotide polymorphisms (SNPs) within the SLC45A2/MATP, SLC24A5/NCKX5, and OCA2/P genes have been associated with natural variation of pigmentation traits in human populations. Here, we describe the characterization of human primary melanocytic cells genotyped for polymorphisms within the MATP, NCKX5, or OCA2 loci. On the basis of genotype, these cultured cells reflect the phenotypes observed by others in terms of both melanin content and tyrosinase (TYR) activity when comparing skin designated as either "White" or "Black". We found a statistically significant association of MATP-374L (darker skin) with higher TYR protein abundance that was not observed for any NCKX5-111 or OCA2 rs12913832 allele. MATP-374L/L homozygous strains displayed significantly lower MATP transcript levels compared to MATP-374F/F homozygous cells, but this did not reach statistical significance based on NCKX5 or OCA2 genotype. Similarly, we observed significantly increased levels of OCA2 mRNA in rs12913832-T (brown eye) homozygotes compared to rs12913832-C (blue eye) homozygous strains, which was not observed for MATP or NCKX5 gene transcripts. In genotype-phenotype associations performed on a collection of 226 southern European individuals using these same SNPs, we were able to show strong correlations in MATP-L374F, OCA2, and melanocortin-1 receptor with skin, eye, and hair color variation, respectively.
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Newton RA, Roberts DW, Leonard JH, Sturm RA. Human melanocytes expressing MC1R variant alleles show impaired activation of multiple signaling pathways. Peptides 2007; 28:2387-96. [PMID: 18006116 DOI: 10.1016/j.peptides.2007.10.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 10/03/2007] [Accepted: 10/03/2007] [Indexed: 10/22/2022]
Abstract
Variant alleles of the human MC1R gene are strongly associated with red hair color, fair skin and poor tanning ability (RHC-trait). Recently, we demonstrated that melanocytes harboring RHC-associated alleles have markedly reduced surface expression and/or impaired G-protein coupling of the corresponding receptor protein. The consequences of such a deficit on MC1R-mediated signaling pathways have now been quantitatively evaluated utilizing strains of human primary melanocytes homozygous for RHC-associated variant alleles and comparing responses to wild-type strains. The ability of melanocortin peptides to increase transcription of cAMP-dependent pigmentation genes, including MITF and SLC45A2, was abrogated in melanocytes with RHC-associated variant alleles, an effect that may contribute to the RHC phenotype. Activation of the c-Fos transcription factor gene was also severely compromised, a finding of potential relevance for non-pigmentary roles of MC1R. We also confirmed p38 signaling as an MC1R-regulated pathway and identified a large synergistic interaction between UV irradiation and MC1R stimulation for the activation of p38. This synergism was impaired in melanocytes expressing RHC variants of MC1R which may be relevant for the poor tanning ability associated with individuals possessing these alleles.
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Affiliation(s)
- Richard A Newton
- Melanogenix Group, Institute for Molecular Bioscience, University of Queensland, Brisbane, Qld 4072, Australia
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Käsmann-Kellner B, Seitz B. [Phenotype of the visual system in oculocutaneous and ocular albinism]. Ophthalmologe 2007; 104:648-61. [PMID: 17684749 DOI: 10.1007/s00347-007-1571-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In spite of albinism being one of the visual impairments which has been known for over a century, it has only been known for a few decades that albinism is correlated to severe cerebral morphological developmental alterations. The increasing knowledge about the role of melanin in the development and orientation of cerebral neurons not only renders more insight into albinism, but also a greater insight in the physiological neuronal and cerebral development in man. Concerning the morphological and visual phenotype there are new clinical findings which enlarge the known spectrum of albinism. In a representative group of 506 persons with oculocutaneous and ocular albinism who are in care at the Department of Ophthalmology at the University of Saarland (UKS), we present a staging of morphological findings of the iris, retinal pigment epithelium and macula, and of the optic nerve head which has been in use for 10 years. Albinism may present with a remarkably mild ocular phenotype and a near to normal functional phenotype. We present correlations between molecular genetic types of albinism, ocular phenotype and visual function. Of great importance concerning later visual acuity is the dysplasia of the optic nerve head (ONH), which is a frequent finding in albinism. The appearance of the ONH should always be included in any clinical description of an albinism patient. It is highly possible that due to a moderate phenotype there are still many patients who have not been diagnosed yet. Visual acuity of 30/20 to 20/20 and no nystagmus do not rule out albinism. In addition, when performing albino VEPs in phenotypically normal children with infantile strabismus, small ONHs, but normal visual acuity and no nystagmus, the classical atypical chiasmal crossing is sometimes found. Therefore, the number of persons having undiagnosed albinism is probably quite high, perhaps there even is a very broad transition zone from normal to albinotic.
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Affiliation(s)
- B Käsmann-Kellner
- Klinik für Augenheilkunde im Universitätsklinikum des Saarlandes UKS, Kirrbergerstrasse 1, 66424, Homburg (Saar), Deutschland.
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