Dysplasia of the corpus callosum in identical twins with nonketotic hyperglycinemia.

Nonketotic hyperglycinemia (NKH) is an autosomal recessively inherited disorder of the glycine degradation pathway leading to accumulation of glycine in body fluids and tissues. Identical twins with nonketotic hyperglycinemia and dysplasia of the corpus callosum are described in support of the hypothesis that some patients with NKH have a genetic defect of the glycine degradation pathway resulting in abnormal corpus callosal development. It is important to screen for metabolic defects whenever similar structural defects are present.