This study includes patients who are at high risk of post-ERCP pancreatitis. Blood samples will be gathered to investigate the possible genetic variation associated with post-ERCP pancreatitis using whole genome sequencing. DNA for whole genome sequencing will be extracted using DNA extraction kit (Qiagen Inc., Hinden, Germany) and the concentration & purity of DNA will be measured using Nanodrop (Nano Drop Technologies, Wilmington, DE, USA) or fluorometric quantitation(Qubit fluorometer). Genetic variations which are associated with acute pancreatitis will be searched using whole genome sequencing. Post-ERCP pancreatitis is the primary outcome. Medical records and data of genetic variations will be reviewed for identifying possible risk factors and genetic variations associated with post-ERCP pancreatitis.