描述
Methionine adenosyltransferase (MAT; Hypermethioninemia; MAT I/III deficiency) deficiency is caused by mutations in the MAT1A gene which causes isolated hypermethioninemia. MAT catalyzes the formation of adenosylmethionine from methionine and ATP. Adenosylmethionine is an important methyl donor in most transmethylation reactions. MAT dificiency is characterized by increased homocysteine and methionine levels in plasma; and accumulation of methionine in urine. Symptoms include dystonia, mental retardation and unusual odor.