As for the neonates, they are polycythemic in case the Hb of their central vein is more than 22 g/dL and the HCT is around over 65%.[3] In some cases, high Hb is combined by erythrocytosis which is an increase in the red blood cell mass.[4] At a normal homeostatic condition, the red blood cell (RBC) mass is below 36 mL/kg in men and 32 mL/kg in women. The gene discussed is GSTM1; the disease is polycythemia.