Hypermethioninemia with S-Adenosylhomocysteine Hydrolase Deficiency, also known as hypermethioninemia with deficiency of s-adenosylhomocysteine hydrolase, is related to s-adenosylhomocysteine hydrolase deficiency. An important gene associated with Hypermethioninemia with S-Adenosylhomocysteine Hydrolase Deficiency is AHCY (Adenosylhomocysteinase). Related phenotypes are hypotonia and global developmental delay