William Leo Nyhan, an American physician and co-discoverer of Lesch-Nyhan syndrome, died on February 11, 2026, at age 99.
Born in Boston on March 13, 1926, he later served as professor of pediatrics at the University of California, San Diego School of Medicine in La Jolla, California. He also held positions at Johns Hopkins School of Medicine and the Miller School of Medicine at the University of Miami, and served on advisory committees, pediatric advisory boards and research foundation boards.
His research included amino acid metabolism disorders such as 4-hydroxybutyric aciduria, 3-methylglutaconyl-CoA hydratase deficiency, multiple carboxylase deficiency, methylmalonic acidemia and propionic acidemia.
William Leo Nyhan (March 13, 1926 – February 11, 2026) was an American physician best known as the co-discoverer of Lesch–Nyhan syndrome.