Filaggrin, claudins, occludins-encoding genes, serine protease inhibitor gene (SPINK-5/LEKT1, cystatin A), mast cell chymase gene (CMA1), epidermal chymo-trypsin and trypsin gene, epidermal N-methyltransferase gene are all involved in the pathogenesis of AD at the level of the defective epidermal barrier [65]. The gene discussed is FLG; the disease is Alzheimer disease.