Adjustment for MTHFR C677T polymorphism genotype did not significantly alter the association between TS 1494del6 and adenoma risk; however, when stratified by both TS 1494del6 and MTHFR C677T genotypes, the reduced risk associated with the del/del genotype was confined to individuals with CC genotype (OR 0.31; 95% CI; 0.15–0.63 for CC genotype individuals, and OR 1.02; 95% CI: 0.43–2.40 for CT/TT genotypes, Pinteraction=0.07). Here, MTHFR is linked to adenoma.