Cobalamin C defect presenting as severe neonatal hyperammonemia

Eur J Pediatr. 2011 Jul;170(7):887-90. doi: 10.1007/s00431-010-1371-8. Epub 2010 Dec 10.

Abstract

Cobalamin C (Cbl-C) defect is the most common inborn error of cobalamin metabolism which causes a block in the pathway responsible for the synthesis of its two metabolically active forms methyl- and adenosylcobalamin. Cbl-C defect causes the accumulation of methylmalonic acid and homocysteine and decreased methionine synthesis. The clinical presentation of patients with early-onset Cbl-C defect, characterized by a multisystem disease with severe neurological, ocular, hematological, renal, gastrointestinal, cardiac, and pulmonary manifestations, differs considerably from what observed in the "classical" form of methylmalonic aciduria caused by defect of methylmalonyl-CoA mutase. This last condition is in most cases dominated in the neonatal period by a metabolic encephalopathy "intoxication type" with severe hyperammonemia and ketoacidosis. We report a Cbl-C defect patient presenting a neonatal encephalopathy with severe hyperammonemia and ketoacidosis who was successfully treated with peritoneal dialysis.

Conclusion: To the best of our knowledge, there are no reported cases of Cbl-C defect showing an acute presentation resembling a classical methylmalonic aciduria. This observation enlarges the spectrum of inherited diseases to be considered in the differential diagnosis of neonatal hyperammonemia.

Publication types

  • Case Reports

MeSH terms

  • Amino Acid Metabolism, Inborn Errors / complications
  • Amino Acid Metabolism, Inborn Errors / diagnosis*
  • Diagnosis, Differential
  • Female
  • Homocystinuria / complications
  • Homocystinuria / diagnosis*
  • Humans
  • Hyperammonemia / etiology*
  • Infant, Newborn
  • Vitamin B 12 Deficiency / congenital

Supplementary concepts

  • Methylmalonic acidemia with homocystinuria