Lesch-Nyhan Syndrome

Lesch-Nyhan syndrome, also known as Nyhan's syndrome, Kelley-Seegmiller syndrome and Juvenile gout:546, is a rare, inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT), produced by mutations in the HPRT gene. The lack of HGPRT causes a build-up of uric acid in all body fluids: both hyperuricemia and hyperuricosuria, which lead to problems such as severe gout and kidney problems, poor muscle control, and moderate mental retardation. These complications usually appear in the first year of life. A striking feature of LNS is self-mutilating behaviors, characterized by lip and finger biting, that begin in the second year of life. Neurological symptoms include facial grimacing, involuntary writhing, and repetitive movements of the arms and legs similar to those seen in Huntington's disease. The direct cause of the neurological abnormalities remains unknown. Because a lack of HGPRT causes the body to poorly utilize vitamin B12, some boys may develop megaloblastic anemia.