There are numerous different asthma phenotypes, such as exercise-induced asthma and severe asthma. How does understanding the specific asthma phenotype help indicate which therapies might work best for a patient? What are the various biomarkers that can indicate asthma, and which ones can be used clincially? Dr. William Calhoun, chair of internal medicine and vice chair for research in the department of internal medicine at the University of Texas Medical Branch in Galveston, Texas, discusses the relationship between asthma phenotypes and biomarkers with host Dr. Ketan Sheth.