FLG mutation-related AD shows distinctive phenotypic features, which include: early-onset AD, increased AD severity, persistent disease, the predilection of cheek and hand lesions, palmar hyperlinearity, increased risk of herpetic eczema and Staphylococcus (S.)aureus-mediated skin infections, increased risk of allergic sensitization and asthma (including treatment-resistant asthma), and FA occurrence [38,39]. The gene discussed is FLG; the disease is asthma.