GSTM1 and sickle cell disease: In particular, X-ray crystallography has played a pivotal role in understanding Hb allostery and for sickle cell disease drug discovery, with Don Abraham as one of the pioneer in the use of this technique (Abraham et al., 1982; Abraham et al., 1983a; Abraham et al., 1983b; Abraham et al., 1984a; Abraham et al., 1984b; Abraham, 1984).