We did not compare frequencies of CLA+ T cells between AD patients and HC in peripheral circulation, however, in agreement with previous reports25, we found abundant infiltrates of CLA+ cells in the lesional skin biopsy specimens of the AD patients compared to HC (Fig. 6a-c), which were also dominated by CD3+ and CD4+ cells in consecutive sections (data not shown). This evidence concerns the gene CD4 and Alzheimer disease.