n :  a rare and usu. fatal genetic disorder of male children that is inherited as an X-linked recessive trait and is characterized by hyperuricemia, mental retardation, spasticity, compulsive biting of the lips and fingers, and a deficiency of hypoxanthine-guanine phosphoribosyltransferase - called also Lesch-Nyhan disease 
 
Lesch, Michael (b 1939), and Nyhan, William Leo (b 1926), American pediatricians. Nyhan held the position of professor of pediatrics at several medical schools, including Johns Hopkins. He had a major interest in the disorders of amino acid metabolism and routinely analyzed blood and urine for amino acids. The urine of a pair of patients, two brothers, was found to contain urate crystals. In addition, the brothers were suffering from an obvious but bizarre neurological disorder. Nyhan, with the help of Lesch, a student research assistant, began investigating urate metabolism and the characteristics of the previously unrecognized genetic disorder exhibited by their two cases. Lesch published a description of the Lesch-Nyhan syndrome in 1964. This report laid the groundwork for the discovery in 1967 of the absence of hypoxanthine-guanine phosphoribosyltransferase in children affected with the syndrome.
 
 
 
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