Lifestyle, hormones, age, environment, and genetics are all contributing factors to how individuals respond to medications. Genetics play a large role and even a single mutation in a protein can alter how they respond to treatments. A well studied example of this is a mutation found in the beta-2 adrenergic receptor, also known as ADRB2. Functional polymorphisms of ADRB2 have been shown to lead to diseases such as asthma and chronic obstructive pulmonary diseases (COPD). Both asthma and COPD are widely studied and several medications are on the market that effectively treat these diseases. A single mutation in ADRB2 can alter how patients with asthma, COPD, or other breathing problems, respond to these otherwise effective treatments. Specifically, the Thr164Ile mutation changes the affinity of said drugs to the ADRB2 receptor, making them less effective. Determining one's genetic makeup can determine what medications will be most effective for them.
