CYP2C19 and transient ischemic attack: For patients with non-cardioembolic minor IS (NIHSS score ≤3) or high-risk TIA (ABCD2 score ≤4) who present within 24 hours of symptom onset, if CYP2C19 gene can be tested and the patient carries CYP2C19 LoF alleles, ticagrelor plus aspirin for 21 days (ticagrelor loading dose of 180 mg on the first day, followed by 90 mg two times per day), and continue with ticagrelor monotherapy (90 mg two times per day) for 90 days are recommended.