title: A report of two families with sarcosinaemia in Hong Kong and revisiting the pathogenetic potential of hypersarcosinaemia.
abstract: BACKGROUND
  Sarcosinaemia is a rare metabolic disorder which has not been reported in Asia.
  
  
  METHODS
  The urine samples of 2 patients were screened as a routine metabolic screening offered for patients with mental retardation in our hospital. We used gas chromatography-mass spectrometry (GC-MS) which is capable of detecting abnormal pattern in amino acids and organic acids. Plasma sarcosine level was further quantified by GC-MS. The same methods were used in the investigations of asymptomatic family members. Urine examination by GC-MS revealed excessive amount of sarcosine in urine (normally undetectable) and their plasma sarcosine levels were raised. The 2 differential diagnoses of presence of sarcosine in urine--glutaric aciduria type II and folate deficiency--were ruled out by the absence of abnormal organic acids in the initial urine screen and by normal serum folate level respectively. Screening of the 2 families identified excessive sarcosine in urine in 2 siblings, one from each family. However, these 2 siblings of indexed patients thus identified have no neurological or developmental problem.
  
  
  CONCLUSIONS
  Our finding was consistent with the notion that sarcosinaemia is a benign condition picked up coincidentally during screening for mental retardation.
authors.affiliation: Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong SAR, People's Republic of China. leesyr@netvigator.com
authors.forename: Shing-Yan
authors.initials: SY
authors.lastname: Lee
authors.forename: Kwok-Yin
authors.initials: KY
authors.lastname: Chan
authors.forename: Albert Y W
authors.initials: AY
authors.lastname: Chan
authors.forename: Chi-Kong
authors.initials: CK
authors.lastname: Lai
mesh_terms: D000592:Amino Acid Metabolism, Inborn Errors / Q000150:complications / Q000175:diagnosis; D002648:Child; D002675:Child, Preschool; D002681:China / Q000208:ethnology; D005192:Family Health; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006723:Hong Kong; D006801:Humans; D007194:India / Q000208:ethnology; D008607:Intellectual Disability / Q000150:complications; D012521:Sarcosine / Q000097:blood / Q000652:urine*; D050892:Sarcosine Dehydrogenase / Q000172:deficiency*
chemical_list: D050892:Sarcosine Dehydrogenase; D012521:Sarcosine