Eosinophil peroxidase is a human gene encoded by the symbol, EPX. It may also be known as: EPO; EPP; EPX-PEN. The encoded protein is an enzyme with an amino acid length of 715 and a mass of 81.0 kDa. Other isoforms may exist. Eosinophil peroxidase is a member of the Peroxidase family, XPO subfamily. Homologs of this gene exist in other organisms, including: Mouse, Rat, Zebrafish, Frog.