GTP cyclohydrolase I deficiency, a new enzyme defect causing hyperphenylalaninemia with neopterin, biopterin, dopamine, and serotonin deficiencies and muscular hypotonia - Niederwieser, A; Blau, N; Wang, M; Joller, P; Atarés, M; Cardesa-Garcia, J (Eur J Pediatr, 1984)