Family of melanocortin receptor (MCR) genes in mammals—mutations, polymorphisms and phenotypic effects
The melanocortin receptor 4 (MC4R) gene is implicated in the regulation of feeding behaviour and body weight in humans and mice. A missense mutation (Asp298Asn) located in a highly conserved region of this gene has clearly been associated with backfat depth, feed intake and growth rate in different porcine lines. In this work the complete coding region of the gene was sequenced in samples from six pigs of a commercial hybrid line and two polymorphisms were detected at positions 709 (C/T) and 1426 (G/A). The last one corresponds to the missense mutation, and has been genotyped in 333 animals with phenotypic records and 68 out of their 81 parents. An association study of these genotypes with several performance and quality traits was performed within the statistical animal model framework. The results confirmed the effect of the missense mutation on growth and fat deposition traits (live weight at 140d and backfat depth), and supported new effects on carcass composition (loin and shoulder weights) and traits related to fat and meat quality (profile of fatty acids; muscle Minolta L(*), a(*) and H(o) colour parameters). A transmission-disequilibrium test provided no evidence of spurious association due to population stratification.