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. This gene encodes a protein that 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. Several alternatively spliced transcript variants encoding different isoforms have been described for this gene.,HAP1;HAP2;HIP5;HLP;hHLP1,Signal Transduction,Neuroscience,Neurodegenerative Diseases,HAP1