GSTM1 and malaria: So far there have been no formal case control studies to analyse the interaction between Hb E and malaria but population studies in Thailand have suggested that those with the Hb E trait show less severe disease when admitted to hospital with acute P. falciparum malaria.14 Furthermore, convincing in vitro culture studies have shown that the red cells from Hb E heterozygotes, but not homozygotes, are more resistant to invasion by P. falciparum.