MTHFR and obesity due to melanocortin 4 receptor deficiency: A meta-study in a population of pregnant women found that the risk of hypertension was significantly increased in the presence of high air pollution and mutations in the MTHFR gene (Yang, Yang & Shiao, 2018), and a study by Fu et al. (2018) in Chinese children confirmed that there was also an interaction between the MTHFR gene and the effect of obesity on hypertension.