In an attempt at solving this conundrum, Bos et al. have proposed that only AD cases with allergen-specific IgE as a hallmark of atopy (corresponding with extrinsic AD, see below) should be referred to as “atopic dermatitis”, while the variant without atopy (intrinsic AD) should be called “atopiform dermatitis”, hinting at the possibility that these entities may in fact constitute two separate diseases [37]. This evidence concerns the gene IGHE and Alzheimer disease.