Consequently, this enzyme plays a key role in balancing the pool of methyl groups during DNA synthesis and methylation.[50] Huang et al analyzed the association between the MTHFR C677T polymorphism and esophageal cancer risk using the polymerase chain reaction-restriction fragment length polymorphism method.[51] They found that the MTHFR 677T genotype distribution in the moderate or severe esophageal precancerous lesion groups and the T allele in the moderate group were significantly different from those in the mild group. Here, MTHFR is linked to esophageal cancer.