Anti-norrin cystine knot growth factor NDP antibodies are used for the immunodetection of the protein encoded by the NDP gene. In humans, the canonical protein has a reported length of 133 amino acid residues and a mass of 15 kDa. It is known to be a secreted protein. It is reported to be expressed in the outer nuclear, inner nuclear and ganglion cell layers of the retina, and in fetal and adult brain. It is noted to be involved in angiogenesis and the Wnt signaling pathway. The gene encoding this protein is implicated in Norrie disease. Other names for this target antigen include FEVR, ND, norrin, NDP, norrin cystine knot growth factor, Norrie disease (pseudoglioma), and EVR2. Gene orthologs have been identified in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species.