title: Exclusion of two candidate pigment loci, c and b, part of chromosome 11p, and 33 random polymorphic markers as the locus for tyrosinase-positive oculocutaneous albinism.
abstract: The locus for Tyrosinase-Positive Oculocutaneous Albinism (ty-pos OCA) has not yet been localised. The search for the ty-pos OCA locus has included a search for linkage to candidate pigment loci and a candidate chromosomal region, as well as a random search using highly polymorphic markers in 42 families, including 271 individuals of whom 79 are affected. The lod scores for the tyrosinase (TYR) locus (11q14-q21), homologous to the albino locus, c, in the mouse and the CAS2/TRP1 locus (9p22-pter), homologous to the brown locus, b, in the mouse were -5.89 and -7.22, respectively, at a recombination fraction of theta = 0.01, thus excluding them from being the ty-pos OCA locus. In the candidate chromosomal region, 11p, four loci (probes) were tested, SAA (pSAA82), CALC (pHC36), HBB (Gamma-globin haplotype) and an AC repeat polymorphism at the Wilm's Tumour locus (WT1). A portion of 11p was excluded with the following lod scores: pSAA82 lod = -2.05 at theta = 0.10; pHC36 lod = -3.87 at theta = 0.05; gamma-globin haplotype lod = -2.80 at theta = 0.10; and WT1 lod = -2.34 at theta = 0.10. Thirty-three polymorphic markers randomly distributed on 13 different chromosomes were all excluded from close linkage to ty-pos OCA.
authors.affiliation: Department of Human Genetics, School of Pathology, South African Institute for Medical Research, Johannesburg.
authors.forename: M A
authors.initials: MA
authors.lastname: Colman
authors.forename: G
authors.initials: G
authors.lastname: Stevens
authors.forename: M
authors.initials: M
authors.lastname: Ramsay
authors.forename: B
authors.initials: B
authors.lastname: Kwon
authors.forename: T
authors.initials: T
authors.lastname: Jenkins
mesh_terms: D016115:Albinism, Oculocutaneous / Q000235:genetics*; D002880:Chromosomes, Human, Pair 11; D002884:Chromosomes, Human, Pair 15; D005808:Genes, Recessive; D008040:Genetic Linkage; D005819:Genetic Markers; D015894:Genome, Human; D006801:Humans; D014442:Monophenol Monooxygenase / Q000235:genetics; D010860:Pigments, Biological / Q000235:genetics; D016133:Polymerase Chain Reaction
chemical_list: D005819:Genetic Markers; D010860:Pigments, Biological; D014442:Monophenol Monooxygenase