A type of haemolytic ANAEMIA, attacks of which occur within an hour or two of eating broad beans (Vicia fava). It is caused by the individual lacking an essential ENZYME, glucose-6-phosphate dehydrogenase which is necessary for the continued integrity of the red cell. This defect is inherited as a sex-linked dominant trait (see GENETIC DISORDERS). Fourteen per cent of African-Americans are affected, as are 60 per cent of Yemenite Jews. The gene is thought to have persisted because it also offers resistance against MALARIA. These red cells are sensitive not only to fava beans but also to drugs including primaquine, sulphonamides, acetanilide, phenacetin, para-aminosalicylic acid, nitrofurantoin, probenecid and vitamin K analogues, all of which can cause a dangerous reaction.