Biotin responsive multiple carboxylase deficiency presenting as diabetic ketoacidosis

Multiple carboxylase deficiency (MCD) is a rare inherited metabolic disease of biotin dependency due to deficiency of holocarboxylase synthetase (HCS) or biotinidase deficiency. A 30-month-old female patient who presented with the initial features of diabetic ketoacidosis (severe metabolic acidosis, ketosis, and hyperglycemia), lactic acidemia, moderate hyperammonemia, and generalized organic aciduria is described. Associated symptoms and signs included erythematous skin rashes, alopecia and developmental delay. The patient responded dramatically to treatment with biotin (10 mg/day) showing normalization of clinical symptoms and most biochemical abnormalities. Based on the urine organic profile by gas chromatography/ mass spectrometry (GC/MS), the diagnosis of MCD was made. A plasma tandem mass study confirmed this diagnosis. The biotinase activity in serum was normal, indicating that this was a rare case of late-onset HCS deficiency.