CYP27B1 and autoimmune disease: Furthermore, in PBMC of healthy control subjects, the expression of the CYP27B1 gene is dependent on a linkage disequilibrium block on chromosome 12, associated with several autoimmune diseases, as well as reduced expression of CYP27B1 risk allele in tolerizing dendritic cells, which is consistent with reduced vitamin D function contributing to autoimmune disease risk [37].