HLA-DRB1 and acquired polycythemia vera: The presence of DRB1*04:02 (OR=24.69; 95%CI=9.80-62.25; P=2.55*10-11) and DRB1*14:54 (OR=27.07; 95%CI=3.35-218,77; P=0.0011) was significantly higher in group of PV patients compared to controls.