MTHFR and oral cavity squamous cell carcinoma: Ferlazzo N [20]et al. conducted methylation studies by extracting genomic DNA from saliva samples from patients with oral squamous cell carcinoma (OSCC) and healthy controls, and found that p16 and O6-methylguanine-DNA methyltransferase (MGMT) gene promoters in the patient group The methylation frequencies of the methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms were significantly associated with their methylation.