Background: Amino acid disorders are a major group of inborn errors of metabolism (IEM) with variable clinical
presentations. This study was aimed to provide the data of amino acid disorders detected in high-risk
Thai patients referred to our metabolic lab from all over the country.
Methods: From 2001 to 2009, we analyzed amino acids by HPLC in 1214 plasma and cerebrospinal fluid specimens.
These specimens were obtained from patients with clinical suspicion of IEM or with positive newborn
screening. The clinical data of the patients with confirmed diagnoses of amino acid disorders were also analyzed.
Results: Fifty-eight patients were diagnosed with amino acid disorders, including 20 cases (34.5%) with maple
syrup urine disease, 13 (22.4%) with phenylketonuria and hyperphenylalaninemia, 13 (22.4%) with nonketotic
hyperglycinemia, 9 (15.5%) with urea cycle defects, 2 (3.4%) with classical homocystinuria, and 1
(1.7%) with ornithine aminotransferase deficiency. There was considerable delay in diagnoses which led to
poor outcomes in most patients.
Conclusion: The prevalence of amino acid disorders in Thailand is distinct from other countries. This will
guide the selection of the prevalent IEM for the future expansion of newborn screening program in this
country.