• Vol. 35 No. 8, 582–584
  • 15 August 2006

A Report of Two Families with Sarcosinaemia in Hong Kong and Revisiting the Pathogenetic Potential of Hypersarcosinaemia



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Introduction: Sarcosinaemia is a rare metabolic disorder which has not been reported in Asia.

Clinical Picture: 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.

Conclusion: Our finding was consistent with the notion that sarcosinaemia is a benign condition picked up coincidentally during screening for mental retardation.

Sarcosinaemia (OMIN 268900) is an autosomal recessive condition due to the deficiency of sarcosine dehydrogenase (E.C. It is a rare condition with an estimated incidence of 1 in 350,000 in a newborn screening programme.

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