GSTM1 and acquired polycythemia vera: The present case demonstrates that the Hb and Hct values included in the major diagnostic criteria for PV according to the 2016 revised World Health Organization guidelines (Hb >16.5 g/dL in males and >16 g/dL in females, or Hct >49% in males and >48% in females) cannot be relied upon for timely diagnosis of PV in the presence of HBT [2].