Vdr Variants Influence Physical Activity Participation

Abstract

PURPOSE: Because vitamin D receptor (VDR) variants associate with muscle strength, body mass, and blood glucose levels, we examined if the VDR single nucleotide polymorphisms (SNPs) Fok1G>A (rs2228750), Bsm1 G>A (rs1544410), and Taq1 C>T (rs731236) also associate with habitual physical activity levels (PA) in healthy, young adults. METHODS: Caucasian men (n= 163, 24.0±0.4 yr, 25.2±0.4 kg·m2) and women (n= 212, 23.6±0.4 yr, 23.9±0.3 kg·m2) were genotyped for the 3 VDR SNPs. Because VDR Taq1 and VDR Bsm1 are in linkage disequilibrium, we constructed haplotypes of these SNPs. We grouped subjects by VDR Fok1 (Fok1 GG, n= 131; Fok1 GA, n= 178; Fok1 AA, n= 58) genotypes; and VDR Taq1/Bsm1 haplotypes (GT/GT, n= 118) (AC/GT, n= 140) and (AC/AC, n= 44). Each subject completed the Paffenbarger Physical Activity Questionnaire. PA phenotypes included: 1) time/wk spent in vigorous, moderate and light intensity PA, 2) time/wk spent sitting, and 3) kcal expended/wk performing vigorous intensity PA. Multivariate ANCOVA tested differences in PA phenotypes among VDR Fok1 and VDR Taq1/Bsm1 genotype groups by gender with age and body mass index as covariates. RESULTS: Men with Fok1 GG spent fewer hr/wk (29.9±2.3 hr) in light intensity PA than men with Fok1 GA (39.0±1.6 hr) (p<0.05). Women with Fok1 AA spent more hr/wk in light intensity PA (45.6±2.7 hr) than women with the Fok1 GA (34.3±1.6 hr) and Fok1 GG (37.1±1.6 hr) genotypes. Adults with the VDR Taq1/Bsm1 GT/GT haplotype spent fewer hr/wk (6.2±0.8 hr) in vigorous intensity PA than those with the AC/GT haplotype (9.5±0.7 hr) (p<0.01). Those with the VDR Taq1/Bsn1 GT/GT haplotype also expended less kcal/wk in vigorous intensity PA (680.1±151.1 kcal) than those with the AC/AC haplotype (1397.1±245.6 kcal) (p<0.05). CONCLUSIONS: VDR SNP associations with habitual PA are time and intensity dependent and gender specific. Further work is needed to determine the pathways through which VDR functional (Fok1) and non-functional (Taq1/Bsm1) genetic variants influence habitual PA.