very interesting question. the key here is genetics. to start with while it's true sickle cell disease is most commonly found in african-americans it's also found in africans people from the caribbean central and south america some mediterranean countries and people from india. sickle cell disease refers to an abnormality of the red blood cells that cause them to appear crescent-shaped instead of round. the disease is inherited; parents pass it to their children. when children inherit two sickle genes they have the disease. when a child inherits just one sickle gene they do not have the disease but can pass it to their own child if their partner also carries a sickle gene. so quite simply sickle cell anemia is commonly found in african americans because their ancestors have passed it on to them. the same is true of other diseases that afflict certain populations at a higher rate than others such as the genetic disorder cystic fibrosis -- which occurs most commonly among caucasians. hope this helps!
why is sickle cell anemia common in african americans?