Different hemogram perturbations point towards MPN, notably elevation of hematocrit (Hct), hemoglobin (Hb), red blood cells (RBC) count in PV, chronic thrombocytosis in ET, erythroleukocytosis [21], teardrop-shaped RBC in PMF, even thrombocytosis and leukocytosis in the initial phase of PMF. The gene discussed is GSTM1; the disease is essential thrombocythemia.