Djukanovic et al. showed in a phase 2 clinical trial that inhaled administration of recombinant IFN-β effectively prevented virus-induced asthma exacerbations in difficult-to-treat asthmatics, suggesting that, at least in this group, impaired IFN production is associated with the development of asthma exacerbations in response to infection with respiratory viruses [167]. Here, IFNA1 is linked to asthma.