title: Early detection of glutaric aciduria type I by newborn screening in Taiwan.
abstract: OBJECTIVE
  Glutaric aciduria type 1 (GA1) is an inborn error of lysine and tryptophan metabolism. There is a lack of initial diagnostic signs of the disease, but late treatment often results in severe neurologic impairment. In this study, we analyzed the results of screening for GA1 in a Chinese population.
  
  
  METHODS
  Dry blood spots were obtained at about 3 days of age from 357,307 newborns and tested for elevation of glutaryl (C5DC)-carnitine by tandem mass spectroscopy. A second sample of blood spots was required from those cases with abnormal elevation of C5DC-carnitine (higher than the cut-off value) (recall). If the results remained abnormal, those cases were referred for confirmation of the diagnosis and treatment.
  
  
  RESULTS
  Between August 2001 and February 2005, there were 40 cases with C5DC-carnitine more than 0.13 microM (the cut-off value), from whom a second sample of blood spots was obtained (recall rate, 0.02%); two cases were confirmed to be affected by GA1. Because of the low positive prediction rate using this cut-off value, we elevated the cut-off value slightly. Between February 2005 and August 2006, there were eight cases with C5DC-carnitine more than 0.22 microM from whom a second sample of blood spots was obtained (recall rate, 0.01%); three cases were confirmed to be affected by GA1. All five cases with persistent elevation of C5DC-carnitine were referred and diagnosis was confirmed in each, giving an incidence of 1 in 71,461 newborns. There were no false negatives. Magnetic resonance imaging studies obtained from four cases showed frontotemporal atrophy at the time of diagnosis. Two cases were followed for over 1 year, and under treatment with dietary control and carnitine supplementation, both had normal development and neither exhibited a frank episode of encephalopathic crisis.
  
  
  CONCLUSIONS
  With properly established cut-offs, GA1 can be successfully screened for in populations with a low incidence of the disease. Early treatment is likely to improve the outcome of cases discovered by screening.
authors.affiliation: Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Chin-Tung
authors.initials: CT
authors.lastname: Hsieh
authors.forename: Wuh-Liang
authors.initials: WL
authors.lastname: Hwu
authors.forename: Yuan-Te
authors.initials: YT
authors.lastname: Huang
authors.forename: Ai-Chu
authors.initials: AC
authors.lastname: Huang
authors.forename: Shiao-Fang
authors.initials: SF
authors.lastname: Wang
authors.forename: Min-Huei
authors.initials: MH
authors.lastname: Hu
authors.forename: Yin-Hsiu
authors.initials: YH
authors.lastname: Chien
mesh_terms: D000592:Amino Acid Metabolism, Inborn Errors / Q000175:diagnosis*; D044466:Asian People; D050770:Glutaryl-CoA Dehydrogenase / Q000172:deficiency*; D006801:Humans; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods*; D013624:Taiwan; D053719:Tandem Mass Spectrometry
chemical_list: D050770:Glutaryl-CoA Dehydrogenase