A block in glycine cleavage reaction as a common mechanism in ketotic and nonketotic hyperglycinemia.

Abstract

Extract: Our previous study demonstrated a block in glycine cleavage reaction in the liver from two patients with hyperglycinemia of the nonketotic type. The present study extended this work to two other patients with nonketotic hyperglycinemia and a patient with ketotic hyperglycinemia. The liver specimens obtained from these patients by autopsy or biopsy were studied for the activities of glycine cleavage reaction and of serine hydroxymethylase. A low activity of glycine cleavage reaction was found in all three patients with nonketotic or ketotic hyperglycinemia, whereas the activity of serine hydroxymethylase remained within normal limits. Speculation: The present study suggests that a block in the glycine cleavage reaction, either primarily or secondarily, plays an important role in glycine accumulation in both types of hyperglycinemias.