Text Box: NEWBORN SCREENING FOR INHERITED METABOLIC DISORDERS BY GC/MS ANALYSIS OF URINE Yoshida I, Inokuchi T, Aoki K, Tashiro K, Oishi S, Jogo M, Kaneko A, Matsumoto K and Tanaka M Research Institute of Medical Mass Spectrometry and Pediatrics, Kurume University, School of Medicine, Kurume, Japan Objective: To evaluate the usefulness of newborn screening for inherited metabolic disorders by GC/MS method. Methods: Since 1996, we have used newly developed method of urease treatment of urine and GC/MS techniques for newborn screening. We screened 25939 neonates. Results and Discussions: GC/MS has been well established tool in screening for inherited metabolic disorders mainly for organic acidemia since the discovery of isovaleric acidemia by Kay Tanaka in 1966. We found 14 patients in 25939 neonates indicating the incidence of 1 per 1852. Fourteen patients include one patient with citrullinemia, 2 patients with glycerol kinase deficiency, one patient with ornithine transcarbamylase deficiency, 5 patients with 2-ketoadipic aciduria, one patient with methylmalonic acidemia, 2 patients with neuroblastoma and 2 patients with propionic acidemia. The sensitivity was 100% and the specificity was 98.8%. The results obtained suggest that GC/MS method is useful for neonatal metabolic screening especially for the disorders which tandem mass spectrometry can not approach to the diagnosis. 2413