On the other hand, it is important to add that uremia suppresses immune signal-induced CYP27B1 (cytochrome P450 family 27 subfamily B member 1) encoding for 1 α -hydroxylase, which is expressed primarily in kidney proximal tubular epithelial cells, but also in extra-renal tissues, such as immune cells. This evidence concerns the gene CYP27B1 and uremia.