Sickle cell anaemia causes an abnormality in the haemoglobin that makes the red blood cells rigid and sticky. It is caused by a mutation in the genes that tell the body to make haemoglobin. Sickle cell gene is inherited from parents. Both the parents must pass the gene to the child to be affected by the disease.

If only one parent passes the defective gene that child will only be a carrier of the disease which means he will be able to pass the disease to his children but is seldom affected by the disease himself.