Association between polymorphisms in the TRHR gene, fat-Free mass, and muscle strength in older women

Abstract

A previous genome-wide association study suggested that polymorphisms in the thyrotrophinreleasing hormone receptor (TRHR) gene contribute to fat-free mass (FFM) variation. The aim of the present study was to examine the association between polymorphismsin the TRHR gene with FFMand muscle strength in older women. Volunteers (n=241; age=66.65± 5.5 years) underwent quadriceps strength assessment using isokinetics and fat-free mass by dual-energy Xray absorptiometry. TRHR polymorphisms and ancestryinformative markers were genotyped through standard procedures. No significant difference was observed for rs7832552. Regarding the rs16892496, ANCOVA revealed that appendicular fat-free mass (AFFM) and relative AFFM were significantly different between groups (p=0.04 and p=0.05, respectively). Individuals carrying A/A and A/C genotypes respectively showed, on average, an extra 1 kg and 900 g of AFFM when compared to C/C genotype carriers. Also, the C/C genotype group presented a significantly higher chance to have reduced muscle strength. The observations presented here provide further evidence that the rs16892496 polymorphism in the TRHR gene may play a role in FFM variation. Moreover, the results bring the novel insight that this genetic variant can present a modest contribution to muscle strength in older women. © American Aging Association 2013.