Valine-sensitive nonketotic hyperglycinemia

An infant with nonketotic hyperglycinemia (NKH) who developed coma in response to oral valine is described.Valine loading tests confirmed that hyperglycinemia enhances valine toxicity. This valine-sensitive form of NKH was, like previous reports of NKH, associated with deficient conversion of glycine-1- 14 CO 2 to 14 CO 2 . Treatment with sodium benzoate maintained normal plasma glycine levels after the second week of life and prevented brain-stem depression. Additional treatment with a low-valinellow-glycine formula from the third to the tenth month of life did not prevent the development of severe mental deficiency.