Genetic and molecular aspects, as well as variable prevalence among different ethnic groups, also contribute to the observed variations in AD.39,40 Recent large-scale studies integrating GWAS, QTLs, and functional assays have uncovered novel loci associated with skin barrier dysfunction and reaffirmed the pivotal role of genes such as FLG in the pathogenesis of AD.41 This evidence concerns the gene FLG and Alzheimer disease.