An asymptomatic infant with isolated 3-methylcrotonyl-coenzyme: a carboxylase deficiency detected by newborn screening for maple syrup urine disease

Eur J Pediatr. 1997 Sep;156(9):713-5. doi: 10.1007/s004310050696.


We describe an asymptomatic male infant with isolated 3-methylcrotonyl-coenzyme A carboxylase deficiency who came to medical attention by newborn mass screening due to elevated blood leucine. The diagnosis was made by abnormal urinary organic acids at 20 days of age and was confirmed by assay of the carboxylase activities in cultured skin fibroblasts.

Conclusion: More attention should be paid to slight elevations of leucine levels in newborn mass screening. Urinary organic acid analysis should be performed in conspicuous cases.

Publication types

  • Case Reports

MeSH terms

  • Carbon-Carbon Ligases / deficiency*
  • Child, Preschool
  • Combined Modality Therapy
  • Diagnosis, Differential
  • Fibroblasts / enzymology
  • Follow-Up Studies
  • Humans
  • Infant
  • Infant, Newborn
  • Japan
  • Male
  • Maple Syrup Urine Disease / diagnosis
  • Maple Syrup Urine Disease / enzymology
  • Maple Syrup Urine Disease / prevention & control*
  • Neonatal Screening*


  • Carbon-Carbon Ligases
  • methylcrotonoyl-CoA carboxylase