CYP2C19 and ischemic stroke: This study investigates whether patients with ischemic stroke during secondary prophylactic treatment with 75 mg clopidogrel daily carrying the SNPs CYP2C19*2, *3, or *17, or CYP3A4*1G, NR1I2, or P2Y12 [5–9] have a higher risk of HTPR, and whether an increased dosage of clopidogrel can overcome HTPR in these patients, as has been shown for patients with cardiovascular disease (CVD) [10].