Rufous Oculocutaneous Albinism in Southern African Blacks Is Caused by Mutations in the TYRP1 Gene
Prashiela Manga,J. G. R. Kromberg,Neil F. Box,Richard A. Sturm,Trefor Jenkins,Michèle Ramsay +5 more
TLDR
ROCA, which in southern African Blacks is caused by mutations in the TYRP1 gene, therefore should be referred to as "OCA3," since this is the third locus that has been shown to cause an OCA phenotype in humans.Abstract:
Summary Oculocutaneous albinism (OCA) is the most common autosomal recessive disorder among southern African Blacks. There are three forms that account for almost all OCA types in this region. Tyrosinase-positive OCA (OCA2), which is the most common, affects ∼1/3,900 newborns and has a carrier frequency of ∼1/33. It is caused by mutations in the P gene on chromosome 15. Brown OCA (BOCA) and rufous OCA (ROCA) account for the majority of the remaining phenotypes. The prevalence of BOCA is unknown, but for ROCA it is ∼1/8,500. Linkage analysis performed on nine ROCA families showed that ROCA was linked to an intragenic marker at the TYRP1 locus (maximum LOD score=3.80 at θ=.00). Mutation analysis of 19 unrelated ROCA individuals revealed a nonsense mutation at codon 166 (S166X) in 17 (45%) of 38 ROCA chromosomes, and a second mutation (368delA) was found in an additional 19 (50%) of 38 chromosomes; mutations were not identified in the remaining 2 ROCA chromosomes. In one family, two siblings with a phenotypically unclassified form of albinism were found to be compound heterozygotes for mutations (S166X/368delA) at the TYRP1 locus and were heterozygous for a common 2.7-kb deletion in the P gene. These findings have highlighted the influence of genetic background on phenotype, in which the genotype at one locus can be influenced by the genotype at a second locus, leading to a modified phenotype. ROCA, which in southern African Blacks is caused by mutations in the TYRP1 gene, therefore should be referred to as "OCA3," since this is the third locus that has been shown to cause an OCA phenotype in humans.read more
Citations
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Patrick Sulem,Daniel F. Gudbjartsson,Simon N. Stacey,Agnar Helgason,Thorunn Rafnar,Margret Jakobsdottir,Stacy Steinberg,Sigurjon A. Gudjonsson,Arnar Palsson,Gudmar Thorleifsson,Snæbjörn Pálsson,Bardur Sigurgeirsson,Kristin Thorisdottir,Rafn Ragnarsson,Kristrun R. Benediktsdottir,Katja K.H. Aben,Sita H. Vermeulen,Alisa M. Goldstein,Margaret A. Tucker,Lambertus A. Kiemeney,Jón Ólafsson,Jeffrey R. Gulcher,Augustine Kong,Unnur Thorsteinsdottir,Kari Stefansson +24 more
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Mutations in the Human Orthologue of the Mouse underwhite Gene (uw) Underlie a New Form of Oculocutaneous Albinism, OCA4
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TL;DR: The mouse underwhite gene and its human orthologue are identified, which underlies a new form of human OCA, termed "OCA4," and the encoded protein, MATP (for "membrane-associated transporter protein") is predicted to span the membrane 12 times and likely functions as a transporter.
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A gene for the mouse pink-eyed dilution locus and for human type II oculocutaneous albinism
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Book
Advances in Human Genetics
Harry Harris,Kurt Hirschhorn +1 more
TL;DR: This book has five chapters covering peroxisomal diseases, X-linked immunodeficiencies, genetic mutations affecting human lipoproteins and their receptors and enzymes, genetic aspects of cancer, and Gaucher disease.
Journal ArticleDOI
A new enzymatic function in the melanogenic pathway : the 5,6-dihydroxyindole-2-carboxylic acid oxidase activity of tyrosinase-related protein-1 (TRP1)
Celia Jiménez-Cervantes,Francisco Solano,T Kobayashi,K Urabe,V J Hearing,JoséA. Lozano,José C. García-Borrón +6 more
TL;DR: Results suggest that TRP1, the product of the brown locus, is indeed a tyrosinase with DHICA oxidase activity, and could be more directly related to DHICA metabolism than to the first steps of the pathway.
Journal ArticleDOI
A cDNA encoding tyrosinase-related protein maps to the brown locus in mouse
TL;DR: Re recombinant inbred strains are used to localize pMT4 at or close to the mouse brown (b) locus, and it is suggested that the gene mapping to c is the authentic tyrosinase gene, whereas that mapping to b encodes a tyrosInase-related protein.