Haemoglobin E is very common in parts of Southeast Asia where it can reach a carrier frequency of 60-80%. The possible malaria protective effects of this and other inherited haemoglobin abnormalities prevalent in these areas are the main cause of this high prevalence. Mild microcytosis is found in heterozygotes; normal to mild anaemia, reduced red cell survival, reduced MCV, target cells, reduced osmotic fragility in homozygotes. HbE can cause serious disease when co-inherited with a beta-thalassaemia mutation Haemoglobin E beta thalassaemia (HbE beta thalassaemia) has a remarkable variability in clinical expression ranging from a mild form of thalassaemia intermedia to a transfusion dependent condition.