GSTM1 and anemia (phenotype): Of those tested in this age group, 25.3% (158 628/627 361) of females and 29.6% (155 279/524 797) of males had low Hb, giving an anaemia prevalence of 13.8% (158 628/1 151 745) in females and 16.1% (155 279/965 992) in males.