In another study, Miyagaki et al. evaluated the role of CCL18, already used as a severity index in AD and bullous pemphigus, in patients suffering from CTCL; its levels, along with IL-31, are related to a worse prognosis [82], while Singer et al. investigated the correlation between levels of IL-31 and itching severity in patients with CTCL, confirming an increase in IL-31mRNA in the PBMCs in patients who complained of itching [83]. This evidence concerns the gene CCL18 and Alzheimer disease.