The CHANCE-2 trial demonstrated that compared to clopidogrel plus aspirin, the combination of ticagrelor and aspirin modestly lowered the risk of stroke at 90 days in patients with minor ischaemic stroke or TIA who were carriers of CYP2C19 loss-of-function alleles, but with more bleeding events [18]. The gene discussed is CYP2C19; the disease is stroke disorder.