Biotin-Responsive Carboxylase Deficiency Associated with Subnormal Plasma and Urinary Biotin

AN increasing number of patients have been diagnosed as having biotin-responsive multiple carboxylase deficiency._{1 2 3 4 5 6 7 8} This genetic disorder involves defects in the metabolism of biotin and produces deficiencies of at least three biotin-containing carboxylases: propionyl-CoA carboxylase (PCC), 3-methylcrotonyl-CoA carboxylase (MCC), and pyruvate carboxylase (PC). All patients have responded to oral administration of 10 mg or more of biotin per day, with normalization of the clinical and biochemical abnormalities. There appear to be two forms of the disorder: a neonatal form and a juvenile form. The neonatal form presents in the first weeks of life, with metabolic acidosis and ketosis and may. . .