Investigation of several candidate genes for fatness and muscle mass deposition traits in pigs.

Obesity is a complex trait that, in humans, has been the objective of a large number of studies aimed to identify the genetic factors affecting different forms of this disease or being relevant for the related health problems. Mutations in several human genes have been associated to common and severe obesity. In addition, other investigations, combining gene expression and other biological evidences, have demonstrated that different genes may be important in muscle mass development. Starting from these evidences, we used a candidate gene approach to select genes that are worth to be investigated in pigs for association studies with fat and muscle deposition traits. As a first step, we mined pig expressed sequence databases and/or sequence trace records in order to identify porcine sequences for some of these genes. For a first list of selected genes, activin A receptor type II B (ACVR2B), cannabinoid receptor 1 (CNR1), cathepsin K (CTSK), myotubularin-related protein 9 (MTMR9), TBC1 domain family, member 1 (TBC1D1) and tubby (TUB), PCR primers were designed to amplify fragments containing exons and introns. Resequencing was carried out in a panel of 10-12 pigs of different breeds. Single nucleotide polymorphisms (SNPs) were identified in the ACVR2B (4 SNPs), CTSK (1 SNP) and TBC1D1 (4 SNPs) genes. These DNA markers will be used in association studies with fat and meat deposition traits in Italian heavy pigs.