The MTHFR (methylenetetrahydrofolate reductase) gene provides instructions for producing an enzyme that helps process amino acids, specifically folate (vitamin B9) and homocysteine. Variations in the MTHFR gene, known as MTHFR mutations, can impair this enzyme’s function and affect methylation processes, impacting folate metabolism and overall health. Individuals with MTHFR mutations may have higher levels of homocysteine and lower levels of active folate, which can increase the risk of conditions like heart disease, mental health issues, and certain pregnancy complications.