NAD(P)H:quinone oxidoreductase 1 (NQO1) C609T and SOD2 Ala-9Val polymorphisms, for instance, are associated with the risk of UC, GSTM1 or GSTT1 mutations with the progression of IBD, while in patients with UC abnormalities in the activity of GST M1 are related to an early onset and more severe symptoms of the disease. This evidence concerns the gene GSTM1 and inflammatory bowel disease.