The project will be performed in the Department of Gastroenterology and Hepatology in close collabpration with the Department of Genetics at the University Medical Center Groningen (UMCG). The inflammatory bowel disease research group, to which the present application belongs, is embedded in the Groningen Institute for Gastro Intestinal Genetics and Immunology (3GI) research school within the UMCG. The research section is located in the European Research Institute for the Biology of Ageing (ERIBA) together with other departments that all share a common interest in applying systems biological approaches to the study of the genetic factors involved in human disease and ageing, in human cells and in model organisms. The Weersma and Festen research group focuses on the genetic, microbiological, and immunological underpinnings of gastrointestinal diseases. We aim to integrate large scale genetic data with extensive prospective clinical as well as immunological and microbiome data. The group has identified numerous genetic and microbiological factors influencing the development and disease course of IBD. The research group offers an energetic, dynamic, and international research environment.