Impact of Race/Ethnicity on Platelet Function

Inclusion Criteria: Each subject must fulfill the following criteria in order to be included in the study. * The subject must be capable of understanding the nature of the study and executing an informed consent document. * The subject must be aged 19 years or older. * For healthy subjects, the subject must deny taking any medications that affect platelet function for at least 7 days before blood collection. * For diseased patients, subjects with documented CAD are eligible to participate if they have been treated with antiplatelet therapy of aspirin (81 to 325 mg/day) with and without clopidogrel (75 mg/day) or another P2Y12 antagonist for at least one month. Exclusion Criteria: For healthy volunteers, subjects who fulfill one or more of the following criteria will be excluded from the study. * taking medications for chronic cardiovascular diseases. * illnesses requiring hospitalization or surgery within the last three months. * history of drug or alcohol abuse. * history of recent anemia or thrombocytopenia. * history of excessive bleeding or thrombosis. * pregnancy. For coronary heart disease subjects, subjects who fulfill one or more of the following criteria will be excluded from the study. * illnesses requiring hospitalization or surgery within the last one month. * history of drug or alcohol abuse. * history of recent anemia or thrombocytopenia. * pregnancy. * recent bleeding diathesis * malignancy * renal insufficiency * liver dysfunction * treatment with warfarin or glycoprotein (GP) IIb/IIIa antagonists during the preceding 14 days