Sickle cell disease

Sickle cell anaemia (SCA) is a genetic disease which causes the red-blood cells of a sufferer to be shaped like sickles, insteaed of the normal rounded shape. This causes the cells to become stuck in capilliaries and deprives the body of oxygen.

The sufferers of the illness usually die early because of this lack of oxygen. However the illness has not died out even though it can only be transferred through generations, and most sufferers die before they can reproduce. This is because a by-product of being a carrier for the illness makes you more resistant to malaria. In countries where this is a problem such as Africa, peoples chances of survival actually increase if they carry SCA. So the illness continues.

The gene responsible for SCA is recessive. If two parents who are carriers have children, their is a 1:4 chance of their child developing the illness and a 1:2 chance of their children being carriers.