Methionine adenosyltransferase I/III deficiency: Neurological manifestations and relevance of S-adenosylmethionine

► Methionine adenosyltransferase I/III deficiency shows persistent hypermethioninemia. ► The pathophysiology of depletion of S-adenosylmethionine (SAM) has been postulated. ► Supplementary treatment of SAM can improve neurological problems and myelination.