Genet. Sel. Evol. 34 (2002) 105-116
DOI: 10.1051/gse:2001006

Association of a missense mutation in the bovine leptin gene with carcass fat content and leptin mRNA levels

Fiona C. Buchanan^a, Carolyn J. Fitzsimmons^b, Andrew G. Van Kessel^a, Tracey D. Thue^a, Dianne C. Winkelman-Sim^a and Sheila M. Schmutz<sup>a

a</sup>  Department of Animal and Poultry Science, 51 Campus Drive, University of Saskatchewan, Saskatoon, S7N 5A8, Canada
^b  Department of Animal Science, 2255 Kildee Hall, Iowa State University, Ames, 50011, USA

(Received 16 May 2001; accepted 24 September 2001)

Abstract
Previously, we have shown that alleles of the BM1500 microsatellite, located 3.6 kb downstream of the leptin gene in cattle, were associated with carcass fat measures in a population of 154 unrelated beef bulls. Subsequently, a cytosine (C) to thymine (T) transition that encoded an amino acid change of an arginine to a cysteine was identified in exon 2 of the leptin gene. A PCR-RFLP was designed and allele frequencies in four beef breeds were correlated with levels of carcass fat. The T allele was associated with fatter carcasses and the C allele with leaner carcasses. The frequencies of the SNP alleles among breeds indicated that British breeds have a higher frequency of the T allele whereas the continental breeds have a higher occurrence of the C allele. A ribonuclease protection assay was developed to quantify leptin mRNA in a separate group of animals selected by genotype. Animals homozygous for thymine expressed higher levels of leptin mRNA. This may suggest that the T allele, which adds an extra cysteine to the protein, imparts a partial loss of biological function and hence could be the causative mutation.

Key words: leptin / cattle / obese / fat / marbling

Correspondence and reprints: Fiona C. Buchanan
    e-mail: buchanan@sask.usask.ca

© INRA, EDP Sciences 2002