I is an alias for the gene, Hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1, in humans. Other names include: 3 beta-hydroxysteroid dehydrogenase/Delta 5-->4-isomerase type 1; 3 beta-hydroxysteroid dehydrogenase/Delta 5-->4-isomerase type I; 3-beta-HSD I; Trophoblast antigen FDO161G; 3 beta-hydroxysteroid dehydrogenase/Delta 5->4-isomerase type 1; short chain dehydrogenase/reductase family 11E, member 1; 3BETAHSD; HSDB3; HSDB3A; SDR11E1. The encoded protein is an enzyme with an amino acid length of 373 and a mass of 42.3 kDa. Other isoforms may exist. I is a member of the 3-beta-HSD family. This gene shares homology with other species, including: Mouse, Rat, Zebrafish.