Prenatal Diagnosis of Nonketotic Hyperglycinemia

Abstract

Nonketotic hyperglycinemia is a rare autosomal recessive inborn error of glycine metabolism, characterized by markedly elevated levels of glycine in plasma, urine, and particularly cerebrospinal fluid. The disease carries a grave prognosis, for progressive neurologic deterioration can occur and often results in the early death of an affected neonate. In surviving infants, the clinical signs include muscular hypotonia, myoclonic seizures, severe mental retardation, and death in infancy or childhood. The metabolic defect seems to reside in reduced activity of the glycine-cleavage enzyme system. Several therapeutic approaches have been attempted, including exchange transfusion, dietary restriction of glycine intake, and administration of . . .