 Humans express two 3β-HSD isozymes, HSD3B1 (type I) and HSD3B2 (type II).The type I isoenzyme is expressed in placenta and peripheral tissues, whereas the type II 3β-HSD isoenzyme is expressed in the adrenal gland, ovary, and testis.The systematic name of this enzyme class is 3β-hydroxy-Δ5-steroid