Background：

Degradation of glycine is brought about by the glycine cleavage system， which is composed of four mitochondrial 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). The protein encoded by this gene is the H protein， which transfers the methylamine group of glycine from the P protein to the T protein. Defects in this gene are a cause of nonketotic hyperglycinemia (NKH). Two transcript variants， one protein-coding and the other probably not protein-coding，have been found for this gene. Also， several transcribed and non-transcribed pseudogenes of this gene exist throughout the genome.