A novel polymorphism in the fatty acid desaturase 2 gene (<i>Fads2</i>): A possible role in the basal metabolic rate

Fatty acyl composition of cell membrane lipids, particularly the abundance of highly unsaturated docosahexaenoic fatty acid (22:6n-3, DHA), is likely to be an important predictor of basal metabolic rate (BMR). Our study was performed using two lines of laboratory mice divergently selected for either high or low BMR. We describe a novel single nucleotide polymorphism in the Fads2 gene encoding Δ6-desaturase, a key enzyme in the metabolic pathways of polyunsaturated fatty acids (PUFAs). The allele frequencies of Fads2 were significantly different in both lines of mice. The analysis of genetic distances revealed that the genetic differentiation between the two studied lines developed significantly faster at the Fads2 locus than it did at neutral loci. Such a pattern suggests that the Fads2 polymorphism is related to the variation in BMR, i.e. the direct target of selection. The Fads2 polymorphism significantly affected abundance of several PUFAs; however, the differences in PUFA composition between lines were compatible with the difference in frequency of Fads2 alleles only for DHA. We hypothesize that the polymorphism in the Fads2 gene affects the BMR through modification of DHA abundance in cell membranes. This may be the first example of a significant link between a polymorphism in a gene responsible for fatty acyl composition and variation in BMR.