Genetic variants of VDR and CYP2R1 affect BMI independently of serum vitamin D concentrations

Background: Vitamin D metabolism and obesity have been linked by several studies, however the reason for this association is unclear. Our objective was to investigate potential correlations between genetic variants in key enzymes of vitamin D metabolism and body mass index on a representative sample of the Hungarian adult population. Methods: Altogether 462 severely vitamin D deficient individuals were studied at the end of winter to minimize environmental and maximize any relevant genetic effect. Furthermore, participants with lifestyle factors known to affect vitamin D metabolism were also excluded. We selected 23 target SNPs in five genes that encode key proteins of vitamin D metabolism (NADSYN1, GC, CYP24A1, CYP2R1, VDR). Results: Variants in 2 genetic polymorphisms; rs2853564 (VDR) and rs11023374 (CYP2R1) showed a significant association with participants‘ BMI levels . These associations survived further adjustment for total-, free-, or bioactive-25(OH) vitamin D levels, although the variance explained by these 2 SNPS in BMI heterogeneity was only 3.2%. Conclusion: Our results show two novel examples of the relationship between genetics of vitamin D and BMI, highlighting the potential role of vitamin D metabolism in the physiology of obesity.