| An inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, encephalopathy and sometimes, developmental delay, and associated with homocystinuria and hyperhomocysteinemia. There are three types of homocystinuria without methylmalonic aciduria; cblE, cblG and cblD-variant 1 (cblDv1). These disorders are caused by a functional deficiency of the cytoplasmic enzyme methionine synthase (MS), which catalyzes remethylation of homocysteine to form methionine. |
