CYP27B1 and immune system disorder: Similarly, polymorphisms of vitamin D alpha-hydroxylase (CYP)1alpha, a key enzyme for regulating both systemic and tissue levels of 1, 25-dihydroxyvitamin D3 [23], did not correlate with known auto-immune disorders such as type 1 diabetes mellitus, Grave’s disease and Hashimoto’s thyroidits among Caucasian pedigrees [24].