To understand the biosynthetic alterations of phosphatidylcholine in HD, we examined the expression levels and activities of a panel of key enzymes responsible for phosphatidylcholine metabolism. The results showed down-regulation of PCYT1A and increased activity of phospholipase A2 in HD leukocytes. These metabolic profiles strongly indicate that disturbed metabolism is involved in pathogenesis of HD and provide clue for the development of novel treatment strategies for HD.