The possible driving role of intestinal immunity in the pathogenesis of AS is indirectly confirmed by the susceptibility genes for Crohn’s disease (CD), a form of inflammatory bowel disease akin to the colitis observed in SpA, whose list includes a number of Th17-associated genes (CCR6, JAK2, TYK2, STAT3 and IL23R; Anderson et al., 2011). This evidence concerns the gene IL23R and inflammatory bowel disease.