title: Analysis of inborn errors of metabolism: disease spectrum for expanded newborn screening in Hong Kong.
abstract: BACKGROUND
  Data of classical inborn errors of metabolism (IEM) of amino acids, organic acids and fatty acid oxidation are largely lacking in Hong Kong, where mass spectrometry-based expanded newborn screening for IEM has not been initiated. The current study aimed to evaluate the approximate incidence, spectrum and other characteristics of classical IEM in Hong Kong, which would be important in developing an expanded newborn screening program for the local area.
  
  
  METHODS
  The laboratory records of plasma amino acids, plasma acylcarnitines and urine organic acids analyses from year 2005 to 2009 inclusive in three regional chemical pathology laboratories providing biochemical and genetic diagnostic services for IEM were retrospectively reviewed.
  
  
  RESULTS
  Among the cohort, 43 patients were diagnosed of IEM, including 30 cases (69%) of amino acidemias (predominantly citrin deficiency, hyperphenylalaninemia due to 6-pyruvoyl-tetrahydropterin synthase deficiency and tyrosinemia type I), 5 cases (12%) of organic acidemias (predominantly holocarboxylase synthetase deficiency) and 8 cases (19%) of fatty acid oxidation defects (predominantly carnitine-acylcarnitine translocase deficiency). The incidence of classical IEM in Hong Kong was roughly estimated to be at least 1 case per 4122 lives births, or 0.243 cases per 1000 live births. This incidence is similar to those reported worldwide, including the mainland of China. The estimated incidence of hyperphenylalaninemia was 1 in 29 542 live births.
  
  
  CONCLUSIONS
  Our data indicate that it is indisputable for the introduction of expanded newborn screening program in Hong Kong. Since Hong Kong is a metropolitan city, a comprehensive expanded newborn screening program and referral system should be available to serve the neonates born in the area.
authors.affiliation: Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong SAR, China.
authors.forename: Han-Chih Hencher
authors.initials: HC
authors.lastname: Lee
authors.forename: Chloe Miu
authors.initials: CM
authors.lastname: Mak
authors.forename: Ching-Wan
authors.initials: CW
authors.lastname: Lam
authors.forename: Yuet-Ping
authors.initials: YP
authors.lastname: Yuen
authors.forename: Angel On-Kei
authors.initials: AO
authors.lastname: Chan
authors.forename: Chi-Chung
authors.initials: CC
authors.lastname: Shek
authors.forename: Tak-Shing
authors.initials: TS
authors.lastname: Siu
authors.forename: Chi-Kong
authors.initials: CK
authors.lastname: Lai
authors.forename: Chor-Kwan
authors.initials: CK
authors.lastname: Ching
authors.forename: Wai-Kwan
authors.initials: WK
authors.lastname: Siu
authors.forename: Sammy Pak-Lam
authors.initials: SP
authors.lastname: Chen
authors.forename: Chun-Yiu
authors.initials: CY
authors.lastname: Law
authors.forename: Hok-Leung Morris
authors.initials: HL
authors.lastname: Tai
authors.forename: Sidney
authors.initials: S
authors.lastname: Tam
authors.forename: Albert Yan-Wo
authors.initials: AY
authors.lastname: Chan
mesh_terms: D000143:Acids / Q000652:urine; D000596:Amino Acids / Q000097:blood; D002331:Carnitine / Q000031:analogs & derivatives / Q000097:blood; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007231:Infant, Newborn; D008661:Metabolism, Inborn Errors / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000652:urine; D015997:Neonatal Screening / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D000143:Acids; D000596:Amino Acids; C116917:acylcarnitine; D002331:Carnitine