thalassaemia more frequently found in populations from the Mediterranean, from the Middle East or from South East Asia?
The genes involved in haemoglobin conditions are often found in regions of the world where malaria has been common (in the past or the present). This is because people who are carriers (people who carry some normal haemoglobin genes but also some genes involved in haemoglobin conditions, but are themselves healthy) have a slight change in shape to their red blood cells. This change in shape does not affect the function of the red blood cell so they do not have any symptoms. However the change in shape does result in the individual being less susceptible to malaria. In areas where malaria is common, carriers of haemoglobin conditions have a survival advantage. They are less likely than their counterparts to contract malaria and thus more likely to survive and to reproduce. When they have children, they have a 1 in 2 (50%) chance with each child of passing on the gene for the haemoglobin condition. Their children may then pass down the gene to their children; their grandchildren may pass
