GNMT

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.

MedlinePlus Genetics provides information about Prostate cancer

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.