CYP2R1 and type 1 diabetes mellitus: For example, SNPs in NAD synthetase 1/ 7-dehydrocholesterol reductase (NADSYN1/DHCR7) gene locus and SNPs in CYP27B1, CYP2R1 genes and have been associated with type 1 diabetes or with type 1 diabetes related autoantibodies [33,35,38].