FLG and hypersensitivity reaction disease: Skin barrier dysfunction has been linked to loss-of-function mutations in FLG, which lead to allergic sensitization and AD development in childhood, and may be associated with the later development of asthma and allergic diseases.39,56 Genetic alterations, especially in FLG, play a significant role in AD predisposition, with loss-of-function mutations found in approximately 10% of patients, which significantly influences its pathogenesis.40,53