The increased levels of six immune phenotypes were observed to be causally associated with increased risk of HT P < 0.01, which were CD3 on CM CD8br, CD3 on CD39+ secreting Treg, HLA DR on CD33dim HLA DR+ CD11b−, CD3 on CD4 Treg, CD62L− plasmacytoid DC %DC, and CD3 on CD45RA+ CD4+. This evidence concerns the gene ENTPD1 and hematocrit.