1. Clopidogrel resistance is common in patients of ischemic cerebrovascular disease.
2. Genetic polymorphisms are the most important factors to clopidogrel resistance.
3. The purpose of this study is to find the genes which are the related to clopidogrel resistance.
4. Through gene sequencing, we can filter patient of clopidogrel resistance, so another drug maybe used to avoid the undesired efficacy.

Inclusion Criteria:

• symptomatic ischemic cerebrovascular disease caused by Intracranial atherosclerotic atherosclerosis research database.
• 90 days had a stroke or transient ischemic attack is defined as symptomatic Intracranial atherosclerotic atherosclerosis
• stenosis ≥ 50% (MRI or CT angiography).
• Intracranial vascular stenosis measured according to the method reported Warfarin aspirin symptomatic intracranial disease research.

Exclusion Criteria:

• diffuse intracranial arterial stenosis.
• cranial magnetic resonance imaging shows lesions as the branch artery blockage caused.
• non-atherosclerotic lesions.
• occurred within 6 weeks of vascular lesions in the region of intracranial hemorrhage.
• potential cardiac thrombus source.
• has concurrent intracranial tumors, intracranial aneurysm or arteriovenous malformation.
• ipsilateral extracranial carotid or vertebral artery stenosis ≥ 50%;
• known to heparin, aspirin, clopidogrel, anesthetics and contrast agents contraindications;
• hemoglobin less than 10g/dL, platelet count <100000/dL;
• responsibility left after cerebral vascular-related serious neurological dysfunction (mRS ≥ 3);
• international normalized ratio> 1.5
• there are factors that can not be corrected by bleeding;
• life expectancy <1 year;
• pregnant or lactating women;
• indications Commission determines that the patient is not suitable for the study treatment.

Symptomatic ischemic cerebrovascular disease caused by Intracranial atherosclerotic atherosclerosis research database; 90 days had a stroke or TIA is defined as symptomatic Intracranial atherosclerotic atherosclerosis; Stenosis ≥ 50% (MRI or CT angiography); Intracranial vascular stenosis measured according to the method reported Warfarin aspirin symptomatic intracranial disease research.