Huntington's disease (HD), a neurodegenerative disorder characterized by loss of striatal neurons, is caused by an expansion of a polyglutamine tract in the HD protein huntingtin. It is a progressive disorder that generally begins in middle age with abnormalities of movement, cognition, personality and mood. HAP-1 is highly expressed in brain and shown to mediate the neuropathology of HD. The human protein interacts with huntingtin, with two cytoskeletal proteins (dynactin and pericentriolar autoantigen protein 1), and with a hepatocyte growth factor-regulated tyrosine kinase substrate. The interactions with cytoskeletal proteins and a kinase substrate suggest a role for this protein in vesicular trafficking or organelle transport. Two transcripts encoding different isoforms have been identified but one is a nonsense-mediated decay (NMD) candidate.Synonyms: HAP-1, HAP2, HLP1, Huntingtin-associated protein 1, Neuroan 1