However, a meta-analysis on the relationship between genetic polymorphisms and clopidogrel efficacy for an ischemic stroke or a TIA in 2016 showed that genetic polymorphisms other than CYP2C19 were not associated with clinical outcomes such as stroke recurrence and composite vascular events among patients with an ischemic stroke or a TIA14. Here, CYP2C19 is linked to transient ischemic attack.