FLG loss-of-function mutations occur in 10% of Europeans, imparting an increased risk of AD, food allergy, and asthma.12,13 The overall increase in the risk of AD conferred by a single FLG loss-of-function mutation is approximately 3.3,14 with a significant additional and independent effect conferred by intragenic copy number variations in FLG. 15Importantly, FLG mutations increase the risk of developing asthma only in the presence of AD.13 Here, FLG is linked to asthma.