文本框: IMPORTANCE OF PROMPT DIAGNOSIS AND TREATMENT OF HOLOCARBOXYLASE SYNTHETASE DEFICIENCY IN AN INFANT Yong. C.K.K., Vallance H.D., Lillquist Y. P., Wong L.T.K., Davidson A.G.F. Division of Biochemical Diseases, British Columbia’s Children’s Hospital, Vancouver, BC, Canada A case of biotin-responsive holocarboxylase synthetase (HCS) deficiency is reported on an 11-month old Chinese girl with severe metabolic acidosis. Our patient was delayed in motor and cognitive function. The parents were immigrants of Southern Chinese extraction and non consanguinous. She presented with intractable vomiting, Kussmaul breathing and decreasing sensorium. Blood gas analysis showed severe lactic acidemia. Urine organic acid analysis showed lactic aciduria, ketonuria and excretion of large amounts of propionylglycine and 3-methylcrotonylglycine. Our patient was resuscitated and stabilized by infusion of NaHCO3 at 8 mmol/hour. Thiamine, riboflavin, biotin and co-enzyme Q10 were given by nasogastric feeding. Carnitine was started intravenously. Fibroblasts studies confirmed the lack of HCS activity. Blood acylcarnitine profile by Tandem Mass Spectrometry (TMS) was consistent with HCS deficiency. Biotin was then maintained as sole therapy. After 20 days of treatment, the organic metabolites and acidosis resolved completely. At 6 and 12 months of follow-up her cognitive function and development were normal. Our case demonstrated the importance of early diagnosis and treatment with biotin in order to prevent death from metabolic acidosis or irreversible damage to the central nervous system. We propose the use of biotin as part of the acute resuscitative treatment of all children less than 2 years with severe unexplained lactic acidosis. HCS deficiency is another example of an inborn error of metabolism which can be been detected by neonatal screening by TMS. 1926