IPMN is mostly detected in asymptomatic patients, but sometimes impaired outflow of pancreatic juice induced by hypersecretion of mucin may cause pain, may induce laboratory test abnormalities of pancreatitis and may cause acute pancreatitis itself, and thus, an IPMN may be discovered after an episode of acute pancreatitis. This evidence concerns the gene MUC5AC and acute pancreatitis.