P gene mutations associated with oculocutaneous albinism type II (OCA2)

Authors

  • William S. Oetting,

    Corresponding author
    1. Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
    2. Institute of Human Genetics, University of Minnesota, Minneapolis, Minnesota 55455
    • Department of Medicine – Genetics, MMC 485, 420 Delaware St. S.E., University of Minnesota, Minneapolis, MN 55455
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  • Sarah Savage Garrett,

    1. Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
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  • Marcia Brott,

    1. Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
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  • Richard A. King

    1. Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
    2. Institute of Human Genetics, University of Minnesota, Minneapolis, Minnesota 55455
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Abstract

Oculocutaneous albinism type II (OCA2) is the most common form of albinism in humans. OCA2 has been previously associated with mutations of the P gene, the human homologue to the murine pink-eyed dilution gene. The P gene encodes a 110 kDa protein containing 12 potential membrane spanning domains and is associated with melanosomal membranes. The specific function of the P protein is currently unknown but is thought to be involved in tyrosinase processing and transport. We report nine novel mutations in the P gene associated with OCA2. These include two missense mutations, c.1938A>C (p.Ile646Val) and c.1556T>C (p.Val519Ala); one nonsense mutation c.612G>A (p.Trp204X); five frameshift mutations: c.2372underscore;2373delTC, c.1555delG, c.1938underscore;1939insC, c.2050delT, and c.1045underscore;1046delAT; and a splice site mutation c.1951+1G>A. We also report 12 novel polymorphisms including one amino acid substitution, c.2365underscore;2366GC>CA (p.Ala789Glu). At present, there is no functional assay to determine if a mutation is truly pathogenic. The presence of numerous polymorphisms of the P gene in the coding region, several of which result in amino acid substitutions, makes molecular diagnosis problematic. To ensure accurate molecular diagnosis, further mutational analysis will be necessary to produce a comprehensive list of mutations associated with OCA2. This information will also help define the critical functional domains of the P protein. Mutations associated with OCA2 can be found in the Albinism Database (http://albinismdb.med.umn.edu). © 2005 Wiley-Liss, Inc.

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