MTHFR and hyperhomocysteinemia: In addition, the enzyme methylenetetrahydrofolate reductase (MTHFR), which catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, presents several allelic variants associated to modifications in its activity, resulting in hyperhomocysteinemia as an emerging risk factor for various cardiovascular, cerebrovascular, and neurological diseases along with several cancers (Bailey and Gregory, 1999; Liu et al., 2020).