The AHCY gene provides instructions for producing the enzyme S-adenosylhomocysteine hydrolase. This enzyme is involved in a multistep process that converts S-adenosylhomocysteine to homocysteine and adenosine.
This reaction also plays an important role in regulating the addition of methyl groups, to other substrates during methylation. Methylation is important in many cellular processes. 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.
AHCY is of interest due to its position in the methionine cycle, part of the wider methylation pathway. A major function of the methionine cycle is to produce S-adenosylmethionine (SAM-e). SAM-e is a major methyl donor required for more than 40 different reactions throughout the body ranging from control of DNA methylation to the breakdown of lipids. SAM-e deficiency has been linked with a variety of disorders including depression, arthritis, and fibromyalgia.
The A and/or T allele in this gene can result in the reduction in AHCY activity, leading to a build-up of S-adenosylhomocysteine inhibiting the production of SAM-e. Therefore SAM-e supplementation may be beneficial, although care should be taken to not oversaturate an already overloaded pathway as this may lead to further complications.