MTHFR and esophageal squamous cell carcinoma: The authors showed that the aberrant hypermethylation of p16, MGMT, and hMLH1 promoter genes was associated with the clinical characteristics of esophageal squamous cell cancer, and individuals carrying the MTHFR CT677 or TT677 genotype had a higher frequency of hypermethylation in the MGMT gene in cancer tissues [21,53].