Lethal late onset cblB methylmalonic aciduria

Objective: To alert the physicians to the possibility of a late-onset inborn error of metabolism in an apparently previously healthy patient with acute clinical presentation, Design: Case report. Setting: Pediatric unit and general intensive care unit Patient An apparently previously healthy 12-yr-old female presented acutely with vomiting, fever, bronchopneumonia, and progressive loss of consciousness associated with ketoacidosis, hyperglycemia, and hyperammonemia. She died 3 days later with a diagnosis of insulin-dependent diabetes mellitus, Interventions: Intravenous hydration, glucose and insulin, mechanical ventilation. Measurements and Main Results: Organic acid analysis on a postmortem sample of aqueaus humor revealed high levels of methylmalonic acid. Enzymatic studies on cultured fibroblasts were consistent with the diagnosis of cb/B methylmalonic aciduria. Conclusions: The diagnosis of cb/B methylmalonic aciduria was made in a postmortem patient who died with a misdiagnosis of insulin-dependent diabetes mellitus. Unclear biochemical findings and positive family history should strongly lead to suspicion of an inborn error of metabolism in an apparently previously healthy critically ill patient.