| Lesch-Nyhan syndrome
A disorder of purine metabolism due to deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT); characterized by hyperuricemia, uric acid renal stones, mental retardation, spasticity, choreoathetosis, and self-mutilation of fingers and lips by biting; X-linked inheritance, caused by mutation in the HPRT gene on Xq. | |