Cobalamin C defect associated with hemolytic-uremic syndrome.

We describe a female infant with typical features of the cobalamin C form of combined methylmalonic aciduria and homocystinuria who also had the hemolytic-uremic syndrome with thrombocytopenia, microangiopathic hemolytic anemia, hypertension, and renal failure. Review of this and other described cases of the cobalamin C defect suggests that the hemolytic-uremic syndrome is part of the phenotypic spectrum of this inborn error of cobalamin metabolism.