GSTM1 and anemia (phenotype): PCV and Hb measurements are considered as haematological indicators for classifying the severity of anaemia, with PCVs in the range of 21-30% and Hb 9.5–13 g/dl being considered as mild anaemia, PCVs of 15–20% and Hb 8–9.5 g/dl as moderate anaemia, and <15% PCV and Hb <8 g/dl as severe anaemia [7].