Anti-DDH antibodies are protein reagents that detect specific antigens. The DDH antigen is another term for the human protein aldo-keto reductase family 1 member C1, encoded by the AKR1C1 gene. The protein is known to function in cholesterol metabolism and homeostasis and epithelial cell differentiation, among other biological roles. Canonically, it has an amino acid length of 323 residues and a mass of 36.8 kilodaltons. Its subcellular localization is in the cytoplasm and it is reported to be expressed in all tissues tested including liver, prostate, testis, adrenal gland, brain, uterus, mammary gland and keratinocytes. The DDH protein is a member of the Aldo/keto reductase protein family. Other alias names for DDH include 2-ALPHA-HSD, 20-ALPHA-HSD, and C9.