A congenital abnormality in which the production of red blood corpuscles is disturbed. The proteins used in the production of red cells are abnormal and as a result the corpuscles are also abnormal. This leads to their rapidly being broken down. Thus, thalassaemia is primarily a disturbance in cell production, combined with a form of haemoly-tic anaemia. Persons suffering from thalassaemia sometimes display no symptoms at all and if there are any these are the general symptoms associated with anaemia. Blood transfusions can be used to compensate for the disturbance in blood corpuscle production. An increase in cell breakdown sometimes makes it necessary to remove the spleen. Thalassaemia occurs mainly in the Mediterranean region, but occasionally occurs in Britain.