MTHFR and obesity due to melanocortin 4 receptor deficiency: However, the influence of other potential risk factors (such as age, being overweight/obesity, alcohol drinking, and cigarette smoking) on association between the MTHFR C677T polymorphism and the risk of hypertension received little attention, especially considering that these factors have been shown to, independently or in combination with the MTHFR C677T polymorphism, affect homocysteine levels [22].