Pain is the most frequent cause of suffering and disability in society. Despite considerable involvement of genetic factors in pain sensation and sensitivity, the individual genes involved remain largely unidentified. In this project the investigators will follow patients undergoing elective major surgery for the development of acute and chronic pain. The investigators will search for clinical as well as genetic factors that can predict the development of pain. These can serve as biomarkers to predict acute and chronic pain development and progression in individual patients and help early individual treatment adaptation.