Glycine N-Methyltransferase Deficiency, also known as gnmt deficiency, is related to hypermethioninemia and methionine adenosyltransferase i/iii deficiency. An important gene associated with Glycine N-Methyltransferase Deficiency is GNMT (Glycine N-Methyltransferase), and among its related pathways/superpathways are Metabolism and Regulation of expression of SLITs and ROBOs. Affiliated tissues include liver and brain, and related phenotypes are hepatomegaly and elevated hepatic transaminase