IGHE and Alzheimer disease: In an attempt to connect endotypes with transcriptome data, Martel et al. (152) described that in mild, extrinsic AD (total IgE >200 kU/L; n = 5), the expression of most skin barrier genes, including filaggrin and loricrin, remained unchanged (or moderately upregulated) compared to controls (n = 9), despite the presence of heterozygous mutations in the filaggrin (FLG) gene in majority of patients.