The GNMT gene provides instructions for producing the enzyme glycine N-methyltransferase. This enzyme is involved in a multistep process that breaks down the protein building block (amino acid) methionine. Specifically, glycine N-methyltransferase starts a reaction that converts the compounds glycine and S-adenosylmethionine (also called AdoMet) to N-methylglycine and S-adenosylhomocysteine (also called AdoHcy).
This reaction also helps to control the relative amounts of AdoMet and AdoHcy. The AdoMet to AdoHcy ratio is important in many body processes, including the regulation of other genes by the addition of methyl groups, consisting of one carbon atom and three hydrogen atoms (methylation). Methylation is important in many cellular functions. These include determining whether the instructions in a particular segment of DNA are carried out, regulating reactions involving proteins and lipids, and controlling the processing of chemicals that relay signals in the nervous system (neurotransmitters).
The glycine N-methyltransferase enzyme is also involved in processing toxic compounds in the liver.
Health Conditions Related to Genetic Changes
At least six variants (also called mutations) in the GNMT gene have been described in individuals with hypermethioninemia, which is characterized by an excess of methionine in the blood. Most of these variants substitute one amino acid for another in the N-methyltransferase enzyme, which reduces the enzyme's function. The reduced glycine N-methyltransferase activity resulting from GNMT gene variants impairs the breakdown of methionine, causing it to build up in the blood. Excess methionine can result in neurological problems and other signs and symptoms in some individuals with hypermethioninemia.More About This Health Condition
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Certain inherited variations in the GNMT gene have been associated with an increased risk of liver and prostate cancers. Other GNMT gene variants that have been found in cancerous tumors are acquired during a person's lifetime and are present only in certain cells. These changes, which are called somatic variants, are not inherited. GNMT gene variants likely impair glycine N-methyltransferase functions such as processing potential cancer-causing substances in the liver and helping to regulate other genes, including those responsible for controlling cell growth. When cells grow too rapidly or in an uncontrolled way, a cancerous tumor can form.
Other Names for This Gene
- Glycine Methyltransferase
- Glycine Sarcosine Methyltransferase
- Glycine Sarcosine N-Methyltransferase
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
- Augoustides-Savvopoulou P, Luka Z, Karyda S, Stabler SP, Allen RH, Patsiaoura K, Wagner C, Mudd SH. Glycine N -methyltransferase deficiency: a new patient with a novel mutation. J Inherit Metab Dis. 2003;26(8):745-59. Citation on PubMed
- Bhat R, Bresnick E. Glycine N-methyltransferase is an example of functional diversity. Role as a polycyclic aromatic hydrocarbon-binding receptor. J Biol Chem. 1997 Aug 22;272(34):21221-6. Citation on PubMed
- Biochemistry (fifth edition, 2002): Methionine Metabolism
- Chen SY, Lin JR, Darbha R, Lin P, Liu TY, Chen YM. Glycine N-methyltransferase tumor susceptibility gene in the benzo(a)pyrene-detoxification pathway. Cancer Res. 2004 May 15;64(10):3617-23. Citation on PubMed
- Huang YC, Lee CM, Chen M, Chung MY, Chang YH, Huang WJ, Ho DM, Pan CC, Wu TT, Yang S, Lin MW, Hsieh JT, Chen YM. Haplotypes, loss of heterozygosity, and expression levels of glycine N-methyltransferase in prostate cancer. Clin Cancer Res. 2007 Mar 1;13(5):1412-20. Citation on PubMed
- Luka Z, Capdevila A, Mato JM, Wagner C. A glycine N-methyltransferase knockout mouse model for humans with deficiency of this enzyme. Transgenic Res. 2006 Jun;15(3):393-7. Citation on PubMed or Free article on PubMed Central
- Luka Z, Cerone R, Phillips JA 3rd, Mudd HS, Wagner C. Mutations in human glycine N-methyltransferase give insights into its role in methionine metabolism. Hum Genet. 2002 Jan;110(1):68-74. Epub 2001 Dec 7. Citation on PubMed
- Luka Z, Wagner C. Effect of naturally occurring mutations in human glycine N-methyltransferase on activity and conformation. Biochem Biophys Res Commun. 2003 Dec 26;312(4):1067-72. Citation on PubMed
- Mudd SH, Cerone R, Schiaffino MC, Fantasia AR, Minniti G, Caruso U, Lorini R, Watkins D, Matiaszuk N, Rosenblatt DS, Schwahn B, Rozen R, LeGros L, Kotb M, Capdevila A, Luka Z, Finkelstein JD, Tangerman A, Stabler SP, Allen RH, Wagner C. Glycine N-methyltransferase deficiency: a novel inborn error causing persistent isolated hypermethioninaemia. J Inherit Metab Dis. 2001 Aug;24(4):448-64. Citation on PubMed
- Ogawa H, Gomi T, Takusagawa F, Fujioka M. Structure, function and physiological role of glycine N-methyltransferase. Int J Biochem Cell Biol. 1998 Jan;30(1):13-26. Review. Citation on PubMed
- Smythies JR, Gottfries CG, Regland B. Disturbances of one-carbon metabolism in neuropsychiatric disorders: a review. Biol Psychiatry. 1997 Jan 15;41(2):230-3. Review. Citation on PubMed
- Tseng TL, Shih YP, Huang YC, Wang CK, Chen PH, Chang JG, Yeh KT, Chen YM, Buetow KH. Genotypic and phenotypic characterization of a putative tumor susceptibility gene, GNMT, in liver cancer. Cancer Res. 2003 Feb 1;63(3):647-54. Citation on PubMed