A major focus of this study was the analysis of potential epistatic interactions with key gene variants of the IL-12 and IL-23/Th17 pathway such as IL23R and STAT4. We demonstrated that the IL12B variant rs6887695 is weakly associated with overall IBD susceptibility (p = 0.035), with trends for association with both CD and UC susceptibility. Here, STAT4 is linked to inflammatory bowel disease.