Hyperglycinemia: A Defect in Glycine Cleavage Reaction

A girl with hyperglycinemia of nonketotic type was presented. The liver biopsied from the patient was studied for glycine metabolism. It was found that the yield of 14CO2 from glyeine-l-14C and the rate of 11C incorporation into serine from glyeine-l-14C as well as glycine-2-14C were extremely low in the patient's liver than in control livers, while the patient's liver showed normal activities of serine-hydroxyrnethylase and serine-dehydratase. These findings indicate that the primary lesion of hyperglycinemia of nonketotic type is a defect in the glyeine cleavage reaction which gives rise to the formation of CO2, methylene-tetrahydrofolate and ammonia from glyeine.