This decline should be well tolerated and is consistent with Hb declines seen in falciparum malaria patients in South East Asia, where approximately 60 % of ACT-treated falciparum malaria patients (with unknown G6PD status) have fractional declines in Hb of < 0 to –20 %, and 12 % have a decline exceeding –20 % (W. Taylor, unpublished observations). Here, GSTM1 is linked to Plasmodium falciparum malaria.