MTHFR and hepatitis A virus infection: We pooled seven case–control studies (including 2,435 HCC cases and 1,642 hepatitis/virus related patients) and found an association between MTHFR rs1801133 polymorphism and decreased risk of HCC in hepatitis/virus related patients (recessive model: OR, 0.85; 95%CI, 0.72–0.99; P = 0.035, and allele model: OR, 0.90; 95%CI, 0.81–0.99; P = 0.028, Table 3).