The PVL showed stronger correlation with CD4+ CCR4+ CD26− than CD4+ CCR4+ and CD4+ CCR4+ CD25+ T cells in patients with non‐ATL HTLV‐1 infection as shown in Figure 2D. There was no difference in the relative frequencies of these cells between ACs and patients with HAM (data not shown). This evidence concerns the gene DPP4 and periventricular leukomalacia.