Personalized medicine is based on the concept that predictive tests support clinical decision making, allowing individualized interventions and improving patient outcomes. Genetic data can inform this process. Patients with inflammatory bowel disease (IBD) are more likely to have an increased burden of common genetic variants that explain a fraction of the estimated genetic IBD susceptibility,1 whereas additional common variants are associated with disease prognosis.2 However, current genetic tests based on common variants have not yet reached the clinic because they cannot predict IBD susceptibility and disease progression with high confidence for individual patients.