Get to the Point: Identifying Albinism Mutations in Cats
Tufts' Canine and Feline Breeding and Genetics Conference, 2003
D.L. Imes; A.E. Young; R.A. Grahn; L.A. Lyons
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis
Davis, CA, USA

Temperature sensitive albinisms in domestic cats are autosomal recessive reduced pigment variations that disrupt normal pigmentation in cat fur. Cats have four phenotypes of albinism due to an allelic series of mutations, C>cb>cs>ca. Complete albinism (caca), is recessive to all other alleles and is characterized by a completely white coat color and has been identified in the Siamese breed. Siamese pointing (cscs), a less severe phenotype than complete albinism, is characterized by a white body with pigment production at the "points" or cooler regions of the body, such as the legs, tail, ears, and nose. Burmese pointing (cbcb), the least severe form of albinism, is characterized by normal cat coat color at the points with a lightening effect on the body. The cs and cb alleles are co-dominant allowing for the compound heterozygous phenotype cbcs seen in Tonkinese cats. The original crossing of Siamese and Burmese cats gave rise to today's Tonkinese cat breed. Tonkinese breeders have three distinct names for the albinism phenotypes: point (cscs), mink (cbcs), and full body or solid (cbcb). Tyrosinase (TYR) is responsible for albinism in humans and mice. The TYR gene in cats is on chromosome D1. In most mammals, TYR has 5 exons with a total cDNA size of 1.6 Kb. Feline TYR sequence has been scanned for the mutations causing the albinism phenotypes in cats. We have identified three missense mutations in the TYR gene. Two mutations are found only in Siamese cats and one is only found in Burmese cats. These mutations are being verified in other cat breeds with similar phenotypes and the search is continuing for the complete albinism mutation. These findings will allow breeders to limit their number of test-crosses by genetically testing their cats for the pointing alleles.

Speaker Information
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Robert A. Grahn
School of Veterinary Medicine
University of California, Davis
Davis, CA

Leslie Lyons, PhD
University of California-Davis
School of Veterinary Medicine
Department of Population Health and Reproduction

Amy E. Young
Department of Population Health & Reproduction
School of Veterinary Medicine
University of California at Davis
Davis, CA

D. L. Imes
School of Veterinary Medicine, University of California, Davis
Davis, CA

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