Non-ketotic hyperglycinaemia presenting as pachygyria.

A 2-day-old infant with lethargy and hypoventilation had pachygyria and agenesis of the corpus callosum on CT scan. Increased concentrations of glycine in plasma and CSF, together with an increased CSF/plasma ratio, confirmed a clinical diagnosis of non-ketotic hyperglycinaemia. This is the first report of pachygyria in this disorder, although agenesis of the corpus callosum is well recognized, and non-specific gyral malformations have been described previously. The specific diagnosis of an inborn error of metabolism in infants with structural brain malformations is of critical importance for accurate genetic counseling.