Xanthine Dehydrogenase is a human gene encoded by the symbol, XDH. It may also be known as: Xanthine dehydrogenase/oxidase; Xanthine oxidase; Xanthine oxidoreductase; XOR; XD; Xanthine oxidase; XO. The encoded protein is an enzyme with an amino acid length of 1333 and a mass of 146.4 kDa. Other isoforms may exist. Xanthine Dehydrogenase is a member of the Xanthine dehydrogenase family. Homologs of this gene exist in other organisms, including: Fly, Rat.