The response to clopidogrel may depend on the number of altered alleles of CYP2C19 (gene-dose effect).14,15 Thus, the US Food and Drug Administration–approved drug label (from 2017) gives guidance for CYP2C19 poor metabolizers to use a different platelet P2Y12 inhibitor; however, it does not give dosing guidance for CYP2C19 intermediate metabolizers.16 It is important to understand whether therapy recommendations should differ between intermediate and poor metabolizers with minor stroke and TIA. This evidence concerns the gene CYP2C19 and Stroke.