What is the strongest identifiable predisposing factor for development of asthma?

• A. Viral infections
• B. Exposure to smoke
• C. Atopy
• D. Exercise-induced factors

Answer: (C)

Atopy—the genetic tendency to mount IgE-mediated allergic responses to common environmental allergens—is the strongest identifiable factor that predisposes someone to develop asthma. This hyperresponsiveness to allergens sets up a chronic allergic inflammatory state in the airways, which leads to airway hyperreactivity and the typical asthma symptoms. A personal or family history of atopy, or evidence of sensitization to aeroallergens (positive skin tests or allergen-specific IgE), strongly predicts the likelihood of developing asthma, more so than other factors.

Viral infections and exposure to smoke are important contributors and can worsen or trigger asthma symptoms, but they don’t identify an inherent predisposition as reliably as atopy. Exercise-induced factors usually emerge as triggers in individuals with established asthma rather than as primary predisposing factors.