Orphanet_168598 (Brain demyelination due to methionine adenosyltransferase deficiency) can be described as follows. Hypermethioninemia due to methionine adenosyltransferase deficiency is a very rare metabolic disorder resulting in isolated hepatic hypermethioninemia that is usually benign due to partial inactivation of enzyme activity. Rarely patients have been found to have an odd odor or neurological disorders such as brain demyelination. Also known as: MAT I/III deficiency, MAT deficiency, Methionine adenosyltransferase deficiency.