GSTM1 and anemia: The subject also had a 9-year-old sister (see Fig. 2) with thalassemia minor who was clinically asymptomatic, she had a microcytic anemia without other laboratory abnormalities (Hb 10.0 g/dL, Hct 31.9 %, MCV 58.0 fL, MCH 18.30 pg, HbA2 5.5 %, HbF 2.6 %, HbA 91.9) (see Table 1; Fig. 1a), and she had at least a triplicated alpha globin gene in heterozygosis.