描述
Non Ketotic Hyperglycinemeia (Glycine encephalopathy; Glycine cleavage system deficiency; NKH) is caused by mutations in several genes in the mitochondrial glycine cleavage system. These include the genes encoding P protein (GLDC), T protein (GCST), and, in one case, the H protein (GCSH). Most patients with GCE (Glycine Encephalopathy, or NKH) have a defect in the GLDC gene.The enzyme system for cleavage of glycine (glycine cleavage system), which is confined to the mitochondria, is composed of 4 protein components: P protein (a pyridoxal phosphate-dependent glycine decarboxylase), H protein (a lipoic acid-containing protein), T protein (a tetrahydrofolate-requiring enzyme), and L protein (a lipoamide dehydrogenase). NKH is characterized by accumulation of glycine in plasma, spinal fluid and urine. Symptoms include seizures, respiratory distress, mental retardation, chorea, visual impairment and hydrocephalus.