In my former crowd — Army medics/paramedics, it's common knowledge that sickle cell IS a racial disease. We wouldn't suspect that form of anemia in someone who isn't of Sub-Saharan descent (maybe 95%).
Interesting, I didn't know black Californians make up only 5% of the population. You're right that it's hitting hispanics hard in that state. There are regional factors and also, access to healthcare is a factor. I'm sure it will be studied more as far as the possible medical factor of race.