Lesch–Nyhan syndrome
an X-linked recessive disorder associated with deficiency of the enzyme hypoxanthine–guanine phosphoribosyltransferase, which leads to overproduction of uric acid. Affected individuals have severe kidney problems; moderate cognitive disabilities; and a compulsive, self-mutilating tendency to bite their lips and fingers. Motor development deteriorates after the first 6 to 8 months of life, marked by spasticity, chorea (involuntary jerky movements), and athetosis (sinuous involuntary movements). Also called hereditary choreoathetosis; hereditary hyperuricemia. [described in 1964 by Michael Lesch (1939–2008) and William L. Nyhan (1926– ), U.S. pediatricians]