Plant & Animal Genomes XI Conference

January 11-15, 2003
Town & Country Convention Center
San Diego, CA

Poster: Cattle
            

MITF IS MAPPED TO CATTLE CHROMOSOME 22

Department of Animal and Poultry Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada

Microphthalmia Associated Transcription Factor (MITF) is a gene involved in pigmentation and is believed to affect the expression of tyrosinase (TYR) and tyrosinase related protein 1 (TYRP1). In mice MITF mutations lead to coat color dilutions, white spotting, or complete loss of pigmentation. Other MITF mutations include reduced eye size, failure of secondary bone resorption, reduced numbers of mast cells, and early onset of deafness. MITF contains 9 exons and spans approximately 200 Kb. The entire MITF coding sequence was obtained using cDNA from cattle of several coat colors. The cattle amino acid sequence is 96% homologous to human, 92% homologous to mouse, and 98% homologous to available horse sequence. A single nucleotide polymorphism (SNP) in exon 1 was used to map MITF to BTA22 using the Canadian Beef Reference Herd. This SNP occurred in the start codon and changed a G to an A, altering the start methionine to an isoleucine. Another methionine occurs as the fourth amino acid and provides an alternate start codon. Two other SNPs were also identified. An A to G substitution occurred in the noncoding region of exon 1, 63 bp before the start codon. A silent mutation occurred in exon 9 as well.