In the cerebrovascular field, correlation analysis in the Platelet Reactivity in Acute Non-disabling Cerebrovascular Events (PRINCE) or transient ischemic attack trial showed that patients with minor stroke or TIA carrying the CYP2C19 loss-of-function alleles have a lower proportion of high platelet reactivity when treated with aspirin plus ticagrelor than those with aspirin plus clopidogrel (Wang et al., 2019). Here, CYP2C19 is linked to Stroke.