PKP2 and Alzheimer disease: [53]. Based on the increasing evidence of the skin barrier being a crucial component in the development of human and canine atopic dermatitis [54]–[55], PKP2 serves as an excellent candidate gene. Furthermore, Filaggrin is known as a filament-aggregating protein and it is important for the formation of the stratum corneum, the outermost layer of epidermis [25]. Since the desmosome is one of the best characterized components of the stratum corneum [56] the importance of Filaggrin and Plakophilin 2 for skin structure in the aetiology of AD may be very similar.