Reviewed January 2008
What is the official name of the MTR gene?
The official name of this gene is “5-methyltetrahydrofolate-homocysteine methyltransferase.”
MTR is the gene's official symbol. The MTR gene is also known by other names, listed below.
What is the normal function of the MTR gene?
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, 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.
How are changes in the MTR gene related to health conditions?
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homocystinuria - caused by mutations in the MTR gene
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More than 15 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, which disrupts the enzyme's activity. For example, one of the most common mutations replaces the amino acid proline with the amino acid leucine at position 1173 (written as Pro1173Leu or P1173L). Without functional methionine synthase, homocysteine cannot be converted to methionine. As a result, homocysteine builds up in the bloodstream and methionine is depleted. Some of the excess homocysteine is excreted in urine. Researchers have not determined how altered levels of homocysteine and methionine lead to the health problems associated with homocystinuria.
- other disorders - increased risk from variations of the MTR gene
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A specific version (variant) of the MTR gene has been associated with an increased risk of having a child with spina bifida, a birth defect that affects the spinal cord. Some studies have suggested that the variant also increases the risk of having a child with Down syndrome (a condition characterized by intellectual disability and associated health problems), but other studies found no increased risk. The variant replaces the nucleotide adenine with the nucleotide guanine at position 2756 in the MTR gene (written as A2756G). (Nucleotides are the building blocks of DNA.) Researchers do not know why there may be a connection between the A2576G variant of the MTR gene and the risk of spina bifida or Down syndrome. Many factors, however, play a part in determining the risk of these complex disorders.
Where is the MTR gene located?
Cytogenetic Location: 1q43
Molecular Location on chromosome 1: base pairs 235,025,340 to 235,130,584
The MTR gene is located on the long (q) arm of chromosome 1 at position 43.
More precisely, the MTR gene is located from base pair 235,025,340 to base pair 235,130,584 on chromosome 1.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about MTR?
You and your healthcare professional may find the following resources about MTR helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
- PubMed
- Recent literature
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OMIM - Genetic disorder catalog (3 links)
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What other names do people use for the MTR gene or gene products?
- cobalamin-dependent methionine synthase
- Homocysteine-methyl tetrahydrofolate methyltransferase
- METH_HUMAN
- Methionine Synthase
- 5-methyltetrahydrofolate-homocysteine methyltransferase 1
- 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase
- Tetrahydropteroylglutamate Methyltransferase
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding MTR?
The resources on this site should not be used as a substitute for
professional medical care or advice. Users seeking information about
a personal genetic disease, syndrome, or condition should consult with a qualified
healthcare professional.
See How can I find a genetics professional in my area? in the Handbook.