Hypermethioninemia due to glycine N-methyltransferase deficiency

Hypermethioninemia due to glycine N-methyltransferase deficiency is a rare, genetic inborn error of metabolism characterized by a relatively benign clinical phenotype, with only mild to moderate hepatomegaly reported, in addition to laboratory studies revealing permanent, greatly increased hypermethioninemia, mild to moderate elevation of aminotransferases and highly elevated plasma S-adenosyl-methionine with normal S-adenosylhomocysteine and total homocysteine.