Glucose-6-phosphate dehydrogenase (G6PD) and a number of other human genetic traits including sickle cell anaemia and related haemoglobinopathies are predominantly found in populations living in malaria endemic countries and have been suggested to provide the host protection from severe forms of malaria [5–8] and asymptomatic malaria [9]. The gene discussed is G6PD; the disease is malaria.