Wilson A, et al. - In a retrospective cohort study, infliximab-exposed individuals with inflammatory bowel disease (IBD) (n = 262) were screened for the genetic variation, HLADQA1*05A>G (rs2097432) in order to assess the relationship between HLADQA1*05 and infliximab antibody formation, infliximab loss of response, treatment discontinuation and adverse drug events in individuals with IBD. About 40% of all individuals were HLADQA1*05A>G variant carriers, with 79% of individuals with infliximab antibodies carrying at least one variant allele. In HLADQA1*05A>G variant carriers irrespective of age, gender, weight, dose and co-immunosuppression with an immunomodulator, the risk of infliximab antibody formation was greater. Variant carrier status was related to an heightened risk of infliximab loss of response and discontinuation, however, it is not with infliximab-associated adverse drug incidents. In addition to infliximab loss of response and treatment discontinuation, HLADQA1*05 is independently related to a great risk of infliximab antibody formation. There could be a role for genotype-guided application of combination therapy in IBD.