Patient description: A 39-year-old man came to the clinic with cough and shortness of breath that was not relieved by his inhaler. He had these symptoms for 5 days during the past 2 weeks. He doubled his oral corticosteroids in the past week. He is a chef with a history of asthma for 3 years, suffering from frequent cough, wheezing, and shortness of breath and chest tightness. The symptoms become more bothersome within 1-2 hours of starting work every day and worsen throughout the work week. His symptoms improve within 1-2 hours outside the workplace. Spirometry was performed revealing a forced expiratory volume in the first second (FEV1) of 63% of the predicted. His past medical history is significant for seasonal allergic rhinitis in the summer. He doesn't smoke or use illicit drugs. His family history is significant for asthma in his father and sister. He currently uses inhaled corticosteroid (ICS) and fluticasone 500 mcg/salmeterol 50 mcg, one puff twice daily.

Clinical trial eligibility criteria: eligible ages (years): 5.0-999.0,  Asthma Individuals who self-report Black ancestry (with at least 1 Black grandparent). 2. Able to perform reproducible spirometry according to ATS criteria. 3. Clinical history consistent with asthma. 4. Baseline FEV1≥40% of predicted and/or post-bronchodilator FEV1≥40% of predicted. 5. Asthma confirmed either by: (1) Beta-agonist reversibility to 4 puffs albuterol ≥ 12% OR (2) PC20FEV1 ≤ 16 mg/ml OR (3) an absolute relative change in %predicted FEV1 of ≥ 12% over two measurements documented by repeat spirogram over the previous year 6. Either: A) inadequately controlled on low-, medium or high-dose ICS monotherapy, or low or medium-dose ICS/LABA, or B) well-controlled on medium or high-dose ICS monotherapy, or low-, medium or high-dose ICS/LABA. Inadequate asthma control will be defined as an ACT/c-ACT score <20; well-controlled asthma will be defined as an ACT/c-ACT score ≥20. 7. Stable asthma controller therapy dose (ICS or ICS/LABA) for the 2 weeks prior to enrollment. 8. Non-smoker (total lifetime smoking history < 5 pack-years if <18, or <10 pack-years if ≥18 years of age; no smoking for at least 1 year). 9. For participants ≥18 years of age: Ability to provide informed consent. For participants under 18 years of age: Ability to provide verbal or written assent and ability of parent to provide informed consent  Medical contraindication to LABA or history of adverse reactions to ICS or LABA preparations or any of their ingredients. 2. Current or prior use of medications known to significantly interact with corticosteroid disposition within the two-week period preceding enrollment. 3. Unwilling to provide a blood sample for DNA extraction and genetic analysis. 4. Major medical problems prohibiting study participation, i.e. presence of chronic or active lung disease other than asthma or history of unstable significant medical illness other than asthma, including thyroid disease, diabetes mellitus, Cushing's disease, Addison's disease, hepatic disease, or concurrent medical problems that could require oral corticosteroids during the study or that would place the participant at increased risk. 5. Systemic corticosteroid treatment for any condition within 4 weeks of enrollment or more than five courses of systemic corticosteroids in the past year. 6. History of a life-threatening asthma exacerbation requiring intubation, mechanical ventilation, or resulting in a hypoxic seizure within the last 2 years. 7. History of a respiratory tract infection within 4 weeks of enrollment. 8. If a female of child-bearing potential, failure to practice abstinence or use an acceptable birth control method. 9. Pregnancy or lactation or planning to get pregnant during the course of the trial. 10. Receiving hyposensitization therapy other than an established maintenance regimen defined as a continuous regimen for ≥ 3 months prior to enrollment. 11. Participation in an intervention trial or use of investigative drugs in the past 30 days or plans to enroll in such a trial during the study