From a therapeutic perspective, as G6PD testing is usually not available in malaria endemic areas, the individual patient risk assessment must take into account the factors described earlier (i.e. the prevalence of G6PD deficiency and its likely severity, the sex of the patient, the degree of anaemia, and the probability of relapse), and also an assessment of the patients’ understanding of the risks and when to stop treatment, and the likelihood and feasibility of accessing health care if there is severe haemolysis. The gene discussed is G6PD; the disease is anemia.