The frequency of the TT genotype of MTHFR C677T polymorphism was 2.7-fold higher in UC individuals with pancolitis than in other UC cases, with respective percentages of 27.3 (95% C.I.16.4–42.0) and 10.5 (95% C.I. 6.3–17.1) (P = 0.0123). The gene discussed is MTHFR; the disease is pancolitis.