Hypermethioninemia (MET)



Hypermethioninemia (MET) is a condition that occurs when there is a high amount of methionine in the body. People with MET are unable to break down an amino acid, a building block of proteins, known as methionine, and do not show signs of the condition. However, if MET is untreated, it can cause developmental delays, muscle weakness, and other health problems. Signs of MET include sleeping longer or more often, weak muscle tone, and a cabbage-like smell. Many of these signs may occur when a baby eats foods that the body cannot break down. Early detection and proper treatment can reduce the severity of symptoms.

Condition Type:



Hypermethioninemia (MET) is a rare condition. The exact number of individuals affected is currently unknown.

More Information for Parents:
Also known as:
  • MET
  • Deficiency of methionine adenosyltransferase
  • Glycine N-methyltransferase deficiency
  • GNMT deficiency
  • Hepatic methionine adenosyltransferase deficiency
  • MAT deficiency
  • MET methionine adenosyltransferase deficiency
  • Methionine mia
  • S-adenosylhomocysteine hydrolase deficiency

Core Conditions