Just a bit of an aside, but the reason most sickle cell patients are black is because the syndrome began as an evolutionary mutation in central africa. The mutation makes it impossible for the trypanosoma parasite, which causes malaria, to thrive. Thus, natural selection decided that maybe not getting malaria is worth putting up with some side effects, however severe. There is also a less severe type of sickle cell which only has minor side effects, but still provides the immunity.