Sickle Cell Anemia: It’s Not a ‘Black Disease’
How Sickle Cell is Acquired – Inheritance
As we’ve become more knowledgeable about sickle cell anemia we’ve discovered that it is not infectious but rather genetic. In other words you can’t get sickle cell from exposure to a toxin, infection, virus, or parasite. People with sickle cell are born with the disease. It is inherited when parents pass it on to their children.
Location of Sickle Cell Carriers
Sickle Cell in the United States
We’ve also discovered that sickle cell is, in the United States, very prevalent among dark skinned people and almost completely absent in “white” populations. This is why sickle cell anemia has been, for a very long time, associated with people of dark skin color. This association has been based on the partially correct assumption that sickle cell originates in Africa and those who are of African descent (and therefore very often dark skinned) are the only people who can carry the gene for the disease and pass it on genetically.
Sickle Cell in the World
While it is true that sickle cell is very prevalent in much of Africa it is entirely untrue that it is confined just to that region. In fact sickle cell is prevalent in parts of all of the following areas:
- Mediterranean countries (such as Greece, Turkey, and Italy)
- The Arabian peninsula
- Spanish-speaking regions (South America, Central America, and parts of the Caribbean)
In each region both dark and light skinned people have been found to be sickle cell carriers. The explanation for this particular distribution lies in explanation for the survival of sickle cell over time.
How Sickle Cell Survived
As has already been explained, sickle cell can for various reasons be a fatal disease. You may think, therefore, that over thousands of years most people without any medical assistance would not survive long enough to reproduce and pass on the sickle cell gene. If people don’t live to pass on the gene for the disease wouldn’t it disappear? The answer is yes, if there were no other factors, it probably would have. But somehow sickle cell has remained with us despite its self destructive nature. Scientists have discovered that it was another disease, malaria, which made way for the survival of sickle cell.
Malaria and Sickle Cell
You may ask – how can one disease help another to survive? What we’ve discovered is that where malaria is prevalent in the world (in areas that are now or once were hot and humid – ideal breeding grounds for malaria carrying mosquitoes), sickle cell is also prevalent. This is because people who carry sickle cell genes are more resistant to malaria.
Malaria has been around longer than humans have and has always acted on human populations. Therefore, since our beginning, malaria has been ‘selecting for’ the sickle cell gene (it kills non sickle cell/non malaria resistant people and leaves behind sickle cell carriers to reproduce and pass on the sickle cell gene). This explains why, despite our racial assumptions about sickle cell, the disease is for example rare in South Africa but prevalent in Greece. Sickle cell does not follow dark skin. Sickle cell follows malaria.
To learn more about Sickle Cell Anemia, see these other NetWellness features:
- Sickle Cell Anemia Overview
- Chronic Complications of Sickle Cell
- Treatments for Sickle Cell
- Sickle Cell Variants
- Sickle Cell Classroom and Workplace Guides
For more information:
Go to the Sickle Cell Anemia health topic.