Prion-like protein doppel is a 152 amino acids protein that belongs to the prion family. The protein encoded by this gene is found on chromosome 20, approximately 20 kbp downstream of the gene encoding cellular prion protein, to which it is biochemically and structurally similar. It is a membrane glycosylphosphatidylinositol-anchored glycoprotein that is found predominantly in testis. Mutations in this gene may lead to neurological disorders.