3. Inflammatory bowel disease patients In collaboration with The Department of Medical Gastroenterology, Aalborg University Hospital, there will be recruited approximately 100 patients with ulcerous colitis for blood sampling (28 ml). In collaboration with the Section of Molecular Diagnostics, Clinical Biochemistry, Aalborg University Hospital, the methylation profile of the cell-free DNA promoter regions in plasma will be analysed using methylation specific PCR (Polymerase Chain Reaction) based on an accelerated bisulfite treatment method.