Health Connections
 
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Slide the green arrow to compare the distribution of malaria and sickle cell with the distribution of skin color.  Which maps match best?

Credit: Maps courtesy Science Museum of Minnesota, animation S2N Media, Inc.



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Sickle Cell Disease

Is sickle cell a "black" disease? No. Contrary to popular perception, the gene variant that causes sickle cell disease evolved as a result of its surprising upside malaria resistance. In the malaria belt regions of Africa, the Middle East, southern Europe and South Asia, this gene variant flourished because the benefits of malaria resistance outweighed the negative impact of sickle cell disease.

Why does sickle cell seem to afflict blacks the most? Sickle cell is found more frequently in persons of Middle Eastern, Indian, Mediterranean and African heritage because those geographic regions are most prone to malaria. The gene variant for sickle cell disease is related to malaria, not skin color.

As you can see on the maps to the left, the colored regions showing the incidence of malaria and sickle overlap very closely where there is malaria, there is sickle cell. However, the map showing distribution of skin color does not follow the same pattern there are places where darker skin does not necessarily correspond with malaria or sickle cell.

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