why is a large population of malaria infected regions heterozygous for a sickle cell anemia?
Answers
Explanation:
Sickle cell disease (SCD) affects millions of people around the globe and is the 4th leading cause of deaths in children in many developing countries. It causes a number of health problems, such as attacks of pain, anaemia, swelling in the hands and feet, bacterial infections and stroke. Sickle-cell contributes to a low life expectancy in the developed world of 40 to 60 years.
The disease results in abnormal haemoglobin - the oxygen-carrying protein found in red blood cells – giving the blood cell a rigid, sticky, sickle-like shape that hinders its oxygen-binding properties. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body. A blood and bone marrow transplant is currently the only cure for sickle cell disease, but only a small number of patients are eligible. For the rest, there's no cure but effective treatments can relieve pain, help prevent problems associated with the disease and prolong life.
70 years ago, researchers found a genetic connection to the anatomical abnormalities seen in blood cells. A mutation seemed to be causing the moon-shaped blood cells. The most severe form of the disease occurs when two copies of the mutation are inherited. However, patients with one sickle cell gene, referred to as sickle cell trait, usually do not have any of the signs of the disease and live a normal life, but they can pass the trait on to their children.