Co-inheritance of α-thalassaemia with Hb SS would also be present in the Nigerian population; this may show red cell indices with similar representation of β-thalassaemia trait [34] but when there is reduced/normal Hb A2 with reduced MCV and MCH with elevated Hb F (3-16%), δβ or γδβ thalassaemia may be present [14]. This evidence concerns the gene GSTM1 and thalassemia.