Genetic testing is becoming more and more prevalent in the clinical practice of medicine (vs. research-based medicine). As this small commentary is no place to discuss all of the ethical, moral, scientific, and other applications of genetic testing, I thought I would spend one small paragraph reviewing one genetic test I feel is of great advantage to people. It is called MTHFR genotyping. MTHFR is an enzyme responsible for the proper metabolism of the B vitamin folate, and the potentially toxic amino acid homocysteine. The product of the reaction catalyzed by MTHFR converts homocysteine to methionine, a useful and necessary amino acid. Certain genetic mutations for the gene coding for MTHFR cause this enzyme to have reduced activity and function. This causes elevations in homocysteine, which increase cardiac risk, the risk of stroke, blood clots and, for people taking methotrexate for cancer or arthritis, the methotrexate can become toxic. It also has been associated with depression and other mood disorders. Your doctor can run a simple blood test to see if you have a potentially dangerous genetic variant of the MTHFR genotype. As insurance coverage for the test is questionable, and always changing, one way to see if you may be at risk for the genetic variant is to have your doctor check your homocysteine levels. If homocysteine levels are elevated, the genetic test may be of benefit. Others who may benefit from the test include those with a family history of cardiovascular disease, strokes, blood clots, or depression, and those who are taking methotrexate long term.