When we investigated the MPN biological continuum (Fig 3), we found CXCR3 expression on CD8+ T cells significantly lower in PV with 11% (5.9–20) than in MF with 17% (15–24) (p = 0.011) but not than in ET with 15% (11–22) (p = 0.22). The gene discussed is CXCR3; the disease is acquired polycythemia vera.