GSTM1 and anemia (phenotype): The World Health Organization (WHO) defines anaemia as an Hb level below 13 g/dL for males, 12 g/dL for nonpregnant women, and 11 g/dL for pregnant women; for children aged 6 months to 2 years, anaemia refers to Hb concentrations less than 11 g/dL, whilst for those aged 2 years to 12 years, anaemia refers to Hb concentrations less than 12 g/dL.