No association was found with gender, first-degree familiarity, the type of IBD, age at starting BioS, age at diagnosis, disease location, perianal disease, extraintestinal manifestations, prior surgery, being naïve to anti-TNF-α, switching from the originator, and laboratory parameters (CRP, ESR, Hb, fecal calprotectin). Here, ESR1 is linked to inflammatory bowel disease.