Aberrations in erythrocyte number, size, shape, and content are characteristic features of several pathological conditions such as anemia where the erythrocyte number or Hb amount is inadequate, polycythemia (also known as erythrocytosis), where erythrocytes are in excess, hereditary spherocytosis where erythrocytes are spherical, and sickle cell disease, where erythrocytes attain sickle shape (8, 9, 10, 11). Here, GSTM1 is linked to polycythemia.