One such model is mice lacking fibroblast growth factor receptor (Fgfr)1 and Fgfr2 in keratinocytes (K5-R1/R2 mice), which – like AD patients – exhibit increased transepidermal water loss (TEWL) and epidermal thickening, elevated serum IgE and IgG levels, and an increase in Langerhans cells, dermal T cells and mast cells (Yang et al., 2010; Sulcova et al., 2015). This evidence concerns the gene KRT5 and Alzheimer disease.