GSTM1 and anemia (phenotype): When we compared the median Hb increases in patients with baseline severe anaemia who were initiated on d4T versus AZT, there were similar increases in Hb: (median g/dL [IQR]: 3.7 [1.7- 5.4] vs. 3.1 [1.4- 4.5], p = 0.203).