Prognostic clues and outcome of early treatment of nonketotic hyperglycinemia

Nonketotic hyperglycinemia presenting in the neonatal period is considered a devastating neurological condition. Most patients die soon after birth, and those who survive manifest severe neurological deficits, psychomotor retardation, and convulsions that are difficult to control. These abnormalities probably result from overstimulation of the N-methyl- d-aspartate receptor in the brain. In the present study, we wished to delineate prognostic clues for patients with neonatal (classic) nonketotic hyperglycinemia and to evaluate the results of early treatment with glycine-receptor modulators. The charts of six children treated in our department since 1991 were reviewed for details that might contribute to the prediction of prognosis. Postnatal clinical presentation and initial cerebrospinal fluid and plasma glycine levels were not predictive of outcome, but early treatment with N-methyl- d-aspartate modulators appeared to reduce late neurological complications and probably is as important as treatment with sodium benzoate. Attainment of developmental milestones, however, varies from one patient to another, presumably because of a factor or factors still unknown.