GSTM1 and anemia (phenotype): At baseline 35.9 % study participants had a Hb <10.0 g/dl compared to 16.6 % after 6 months of ART, a statistically significant reduction in risk of anemia RR = 0.56 [(95 % CI 0.44, 077) p < 0.0001] as shown in Table 2.