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

Fiona Buchanan , Carolyn Fitzsimmons , Andrew van Kessel , Tracey Thue , Dianne Winkelman-Sim , Sheila Schmutz

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.

Mots clés: leptin; cattle; obese; fat; marbling

Domaines: Génétique animale

Fiona Buchanan, Carolyn Fitzsimmons, Andrew van Kessel, Tracey Thue, Dianne Winkelman-Sim, et al.. Association of a missense mutation in the bovine leptin gene with carcass fat content and leptin mRNA levels. Genetics Selection Evolution, 2002, 34 (1), pp.105-116. ⟨10.1051/gse:2001006⟩. ⟨hal-00894402⟩