Temporary myoclonus with treatment of congenital transcobalamin 2 deficiency.

The treatment of acquired cobalamin deficiency in infants may result in the development of a syndrome defined by temporary involuntary myoclonic movements. A patient with an inborn error of metabolism resulting in transcobalamin 2 deficiency who was treated with cobalamin and then developed this syndrome is presented. Neurologic investigations were normal. The continuance of cobalamin and avoidance of antiepileptic drugs is recommended. To our knowledge this is the first such case.