Sickle cell anemia is an inherited disease that is caused by erythrocytes (red blood cells) that are sickle-shaped due to mutated hemoglobin, the critical protein that carries oxygen inside erythrocytes. Sickle cell anemia affects each individual differently and can affect every body system and organ to varying degrees. For centuries, it has been observed that individuals with this disease do not get severe malaria infections or die from malaria. This anomaly may have several causes.
The Defective Gene Hemoglobin S Causes Sickle Cell Anemia
Sickle cell anemia is a lifelong disease that is caused by a defective gene called hemoglobin S. This inherited disease is a recessive disorder which means that it must be received from both parents.
Sickle cell anemia does not have a cure and it can’t be prevented. Individuals that receive the hemoglobin S gene from only one parent are carriers of the disease; they will not have symptoms of sickle cell anemia, except very slight symptoms at high altitudes or when there are low levels oxygen in the environment. Sickle cell gene carriers can pass the disease on to their offspring.
Symptoms of sickle cell anemia include fatigue, tiredness, weakness and an increased heart rate. Sickled red blood cells are stiff and can stick together to block and narrowing the blood vessels, leading to cardiovascular diseases such as stroke.
Other symptoms of sickle cell anemia include organ pain, swelling of the hands, spleen damage, infections, chest pain, skin ulcers, slowed healing, jaundice and yellowing of the eyes, a slight and weak build and slowed growth and development particularly in children
The Malaria Link to Sickle Cell Anemia
Sickle cell anemia is thought to have come from a genetic mutation in the early history of humankind. Malaria epidemics in regions where sickle cell anemia was common caused a large number of deaths. However, people with sickle cell anemia or carriers of the disease always survived malaria even if they became infected.
This caused in an increased proportion of the number of people with sickle cell anemia in those areas with malaria outbreaks such as the Indian Subcontinent, sub-Saharan Africa and the Mediterranean. These individuals then passed on the Hemoglobin S gene to their children who were also able to survive malaria.
The Malaria Parasite Cannot Reproduce Properly in Certain Conditions
Though it is not yet known exactly why individuals with sickle cell anemia or just one hemoglobin S gene are able to survive malaria, there are several theories. A study published in the medical journal The Proceedings of the National Academy of Sciences showed that the malaria parasite was paralysed or destroyed by sickled erythrocyte cells.
Sickled red blood cells live for only ten to 20 days, which is much lower than the 120 day lifespan of normal, healthy red blood cells. This may affect the life cycle of the malaria parasite in the body, stopping it from replicating. As the rate at which the infection spreads in the body is drastically slowed, it may give the immune system time to attack and subdue malaria completely.
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Noreen Kassem - Noreen Kassem is a hospital doctor based in London, UK. She has extensive experience in clinical research and an undergraduate honors ...
