You're treating a 56-year-old woman with a history of coronary heart disease, dyslipidemia, and diabetes. She is current

[answerhappygod]

You're treating a 56-year-old woman with a history of coronary
heart disease, dyslipidemia, and diabetes. She is currently taking
the following meds: aspirin 81 mg/day, atorvastatin (Lipitor) 20
mg/day, metformin (Glucophage) 850 mg twice/day, and sitagliptin
(Januvia) 100 mg/day. Due to the results of a recent cardiac
catheterization, she is set to have a cardiac stent placed in one
of her coronary arteries. Because of this, she is going to be
started or clopidogrel (Plavix). Her cardiologist mentions that she
needs to have a genetic test done before starting in one of her
treatments. Why?
Explain your answer please.