Healthcare professionals caring for patients with inflammatory bowel diseases (IBDs) in 2013 are equipped with significantly better knowledge about the disease, its variations, course and complications than in years gone by. Treatment options are improving, and perhaps more importantly, our knowledge of when and how to use existing treatments is becoming sharper. For these reasons, we have decided to publish a special issue of Gut in 2013 focusing on IBD. In this special edition, we have invited leading experts to review the current state of knowledge on six important aspects of IBD.

Perhaps the greatest recent scientific advances, enabled by high-throughput sequencing and other technologies,1 have been a deeper understanding of the genetic factors that are linked to IBD susceptibility in conjunction with alterations in the intestinal microbiome in patients.2 ,3 While much remains to be done in understanding the interactions between the genome and the …