NEWBORN SCREENING Nationwide survey of extended newborn screening by tandem mass spectrometry in Taiwan Dau-Ming Niu & Yin-Hsiu Chien & Chuan-Chi Chiang & Hui-Chen Ho & Wuh-Liang Hwu & Shu-Min Kao & Szu-Hui Chiang & Chuan-Hong Kao & Tze-Tze Liu & Hung Chiang & Kwang-Jen Hsiao Received: 2 February 2010 / Revised: 7 May 2010 / Accepted: 10 May 2010 / Published online: 22 June 2010 # SSIEM and Springer 2010 Abstract In Taiwan, during the period March 2000 to June 2009, 1,495,132 neonates were screened for phenylketonuria (PKU) and homocystinuria (HCU), and 1,321,123 neonates were screened for maple syrup urine disease (MSUD), methylmalonic academia (MMA), medium-chain acyl- coenzyme A (CoA) dehydrogenase (MCAD) deficiency, isovaleric academia (IVA), and glutaric aciduria type 1 (GA-1) using tandem mass spectrometry (MS/MS). In a pilot study, 592,717 neonates were screened for citrullinemia, 3- methylcrotonyl-CoA carboxylase deficiency (3-MCC) and other fatty acid oxidation defects in the MS/MS newborn screening. A total of 170 newborns and four mothers were confirmed to have inborn errors of metabolism. The overall incidence was approximately 1/5,882 (1/6,219 without mothers). The most common inborn errors were defects of phenylalanine metabolism [five classic PKU, 20 mild PKU, 40 mild hyperphenylalaninemia (HPA), and 13 6-pyruvoyl- tetrahydropterin synthase (PTPS) deficiency]. MSUD was the second most common amino acidopathy and, signifi- cantly, most MSUD patients (10/13) belonged to the Austronesian aboriginal tribes of southern Taiwan. The most frequently detected among organic acid disorders was 3- MCC deficiency (14 newborns and four mothers). GA-1 and MMA were the second most common organic acid disorders Communicated by: Georg Hoffmann Competing interests: None declared. Chien YH, Chiang CC and Ho HC made equal contribution as the first author. D.-M. Niu (*) Institute of Clinical Medicine, School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei 112, Taiwan e-mail: dmniu1111@yahoo.com.tw D.-M. Niu : C.-H. Kao Department of Pediatrics, Taipei Veterans General Hospital, Taipei 112, Taiwan Y.-H. Chien : W.-L. Hwu Department of Medical Genetics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan Y.-H. Chien : W.-L. Hwu Department of Pediatrics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan C.-C. Chiang : S.-M. Kao Chinese Foundation of Health, Taipei, Taiwan H.-C. Ho : H. Chiang Taipei Institute of Pathology, Taipei, Taiwan T.-T. Liu Genome Research Center, National Yang-Ming University, Taipei, Taiwan S.-H. Chiang : K.-J. Hsiao (*) Department of Medical Research and Education, Taipei Veterans General Hospital, Bldg 201, Section 2, Shih-Pai Rd, Taipei 112, Taiwan e-mail: hsiao@pmf.tw K.-J. Hsiao Department of Education and Research, Taipei City Hospital, Taipei, Taiwan J Inherit Metab Dis (2010) 33 (Suppl 2):S295–S305 DOI 10.1007/s10545-010-9129-z