MTR gene
The MTR gene provides instructions for making the enzyme methionine synthase, which is essential for processing amino acids in the body.
Normal Function
The MTR gene provides instructions for making an enzyme called methionine synthase. This enzyme plays a role in processing amino acids, the building blocks of proteins. Specifically, methionine synthase carries out a chemical reaction that converts the amino acid homocysteine to another amino acid called methionine. The body uses methionine to make proteins and other important compounds. To function properly, methionine synthase requires methylcobalamin (a form of vitamin B12) and another enzyme called methionine synthase reductase, which is produced from the MTRR gene.
Health Conditions Related to Genetic Changes
Homocystinuria
More than 20 mutations in the MTR gene have been identified in people with homocystinuria. Many of these mutations lead to the production of an abnormally small, nonfunctional version of methionine synthase. Other mutations change single amino acids in the enzyme. One of the most common mutations replaces the amino acid proline with the amino acid leucine at position 1173 (written as Pro1173Leu or P1173L), resulting in an enzyme with reduced function. Without functional methionine synthase, homocysteine cannot be converted to methionine. As a result, homocysteine builds up in the bloodstream, and the amount of methionine is reduced. Some of the excess homocysteine is excreted in urine.
Other disorders
A specific version (variant) of the MTR gene, written as A2756G, has been associated with various health problems before birth. This variant replaces the nucleotide adenine with guanine at a certain location in the gene.
- Neural tube defects: This variant has been associated with an increased risk of birth defects that occur during the development of the brain and spinal cord.
- Down syndrome: Some studies have suggested that the variant increases the risk of having a child with Down syndrome, though other studies have found no increased risk.
Other Names for This Gene
- 5-methyltetrahydrofolate-homocysteine methyltransferase 1
- 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase
- cblG
- cobalamin-dependent methionine synthase
- Homocysteine-methyl tetrahydrofolate methyltransferase
- METH_HUMAN
- Methionine Synthase
- Tetrahydropteroylglutamate Methyltransferase