Hypermethioninemia Due to Adenosine Kinase Deficiency, also known as hypermethioninemia encephalopathy due to adenosine kinase deficiency, is related to hypotonia and glycine n-methyltransferase deficiency. An important gene associated with Hypermethioninemia Due to Adenosine Kinase Deficiency is ADK (Adenosine Kinase). Affiliated tissues include liver and skeletal muscle, and related phenotypes are seizure and failure to thrive