Fig. 1

Number of PubMed citations for ATG16L1, NOD2, IL23R, HLA/MHC, GWAS and autophagy in combination with “inflammatory bowel disease”, “Crohn’s disease” OR “ulcerative colitis” from the years 1997–2015 depicting a steep increase of follow-up studies for genes and pathways after discovery. Interestingly, the HLA/MHC association signal in IBD has been known for a long time, however, studies for this locus in IBD are rarer and no increase can be observed. We think that this region is understudied, given its importance in disease etiology (in particular in ulcerative colitis), calling for more IBD immunogenetics studies in the future