GNMT

The GNMT gene provides instructions for producing the enzyme glycine N-methyltransferase. This enzyme is involved in a multistep process that breaks down the amino acid methionine. 

This reaction 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 neurotransmitters.

The T-allele is associated with higher homocysteine levels. 

Vitamin D3 and healthy testosterone levels are important cofactors for this enzyme.