Recently, the Platelet Reactivity In Non-disabling Cerebrovascular Events (PRINCE) study reported that patients with minor stroke or TIA treated with ticagrelor/aspirin had a lower proportion of high on-treatment platelet reactivity (HOPR), especially in carriers of the CYP2C19 LOF alleles compared with those treated with clopidogrel/aspirin. Here, CYP2C19 is linked to transient ischemic attack.