Exclusion of the acyl CoA:diacylglycerol acyltransferase 1 gene (DGAT1) as a candidate for a fatty acid composition QTL on porcine chromosome 4.

DGAT1 is a microsomal enzyme that catalyses the final step in triglycerides synthesis. DGAT1-deficient mice are viable, lean, fertile and resistant to diet induced obesity. We have previously identified a quantitative trait loci (QTL) on chromosome 4 that affects fatty acid composition in an F2 cross between Iberian x Landrace. The human DGAT1 gene is located on chromosome 8q24.3, this region aligns to porcine chromosome 4, making the pig DGAT1 gene a suggestive positional candidate gene for the QTL. In this study, we sequenced 1679 bp of the mRNA from animals of five pig breeds (Iberian, Landrace, Large White, Piétrian and Meishan) to identify genetic variants. One of the polymorphisms found creates a polymorphic HinfI restriction site and it was genotyped by PCR-RFLP in these five pig breeds. Allele A was not found in the analysed Iberian and Landrace populations, whereas Meishan population presents the highest frequency (35%). The DGAT1 gene was located by radiation hybrid mapping to the porcine chromosome 4, outside the confidence interval for the fatty acid composition QTL and excludes it as a positional candidate gene.