In AD, Th2-chemokines such as CCL26/eotaxin-3 [103,104], CCL22/MDC [105], CCL18/PARC [100,106], CCL27/CTACK [107], and CCL17/TARC, have been more commonly found as blood biomarkers compared to Th2-cytokines [45], the latter of which is considered the most reliable biomarker for AD [66]. This evidence concerns the gene CCL17 and Alzheimer disease.