No association between type 1 diabetes and genetic variation in vitamin D metabolism genes: a Danish study

Background Vitamin D, certain single nucleotide polymorphisms (SNPs) in the vitamin D-receptor (VDR) gene and vitamin D metabolism genes have been associated with type 1 diabetes (T1D). Objective We wanted to examine if the most widely studied SNPs in genes important for production, transport, and action of vitamin D were associated with T1D or to circulating levels of vitamin D 25-hydroxyvitamin D [25(OH)D] in a juvenile Danish population. Methods We genotyped eight SNPs in five vitamin D metabolism genes in 1467 trios. 25(OH)D status were analyzed in 1803 children (907 patients and 896 siblings). Results We did not demonstrate association with T1D for SNPs in the following genes: CYP27B1, VDR, GC, CYP2R1, DHCR7, and CYP24A1. Though, variants in the GC gene were significantly associated with 25(OH)D levels in the joint model. Conclusion Some of the most examined SNPs in vitamin D metabolism genes were not confirmed to be associated with T1D, though 25(OH) levels were associated with variants in the GC gene.