Loss-of-function mutations in the FLG (filaggrin) gene, including p.R501X and c.2282del4, are important risk factors in the etiology of sporadic and familial forms of atopic dermatitis and asthma.34,35 Filaggrin is a filament-aggregating protein, important in the formation of the cornified cell envelope and has a key role in maintaining barrier function. This evidence concerns the gene FLG and asthma.