Cobalamin C Mutation (Methylmalonic Aciduria and Homocystinuria) in Adolescence

DISORDERS of cobalamin (vitamin B12) can be divided into those associated with a deficiency of this essential cofactor and those due to inborn metabolic errors. When they are a result of an inborn error of metabolism, symptoms usually appear in infancy and consist of failure to thrive, developmental retardation, seizures, and hematologic abnormalities.1 2 3 4 5 6 7 8 9 10 In contrast, cobalamin-deficiency disorders generally occur in adulthood and are associated with megaloblastic anemia, subacute combined degeneration, and mental disturbances.11 In this report, we describe an adolescent girl with progressive dementia and myelopathy secondary to a familial intracellular defect of B]2 metabolism (cobalamin C mutation), . . .