Determining Genetic Role in Treatment Response to Anti-Platelet Interventions (The PAPI Study)

Inclusion Criteria: * Of Old Order Amish descent Exclusion Criteria: * Currently pregnant or less than 6 months have passed since delivery * Has a history of a bleeding disorder or major spontaneous bleed, such as peptic ulcer, epistasis, or intracranial bleed * Has severe hypertension, defined by a blood pressure above 160/95 mm Hg, making it unethical not to recommend prompt treatment * Takes medications that would affect the outcome(s) to be measured and cannot willingly and safely, in the opinion of the treating physician and study physician, discontinue these medications for 1 week prior to protocol initiation * Is taking vitamins or other supplements and is unwilling to discontinue their use for at least 1 week prior to study * Has a coexisting malignancy * Has a creatinine level greater than 2.0 mg/dl, aspartate transaminase (AST) or alanine transaminase (ALT) greater than two times the upper limit of normal, hematocrit less than 32%, or a thyroid-stimulating hormone (TSH) less than 0.4 or greater than 5.5 mIU/L * Has a bleeding disorder or history of gastrointestinal bleeding or other major bleeding episode * Is currently taking aspirin, clopidogrel, or other anti-coagulant, such as warfarin, heparin, or GPIIb/IIIa antagonists, and have conditions that might place them at increased risk from withdrawal of these medications 14 days prior to protocol initiation, including history of unstable angina, heart attack, angioplasty (including stent placement), coronary artery bypass surgery, atrial fibrillation, stroke or transient ischemic attacks, diabetes, or deep vein thrombosis or other thrombosis * Has polycythemia, or thrombocytosis, defined by a platelet count greater than 500,000 * Has thrombocytopenia, defined by a platelet count less than 75,000 * Has had surgery within the last 6 months * Has an aspirin or clopidogrel allergy * Currently breast feeding