Around 20% of European ancestry and 40–45% of Asian ancestry populations carry one loss-of-function CYP2C19 allele, with 2% of Europeans and 8–13% of Asians carrying two loss-of-function alleles.31 Data, predominantly from acute coronary syndrome (ACS) and also stroke indications, link the presence of CYP2C19 loss-of-function(s) to poorer outcomes.31 Data are less well established for non-ACS cardiovascular indications32 but research continues in this area.33 Here, CYP2C19 is linked to Stroke.