Oh, no, I know that - it's just not the first thought that enters my mind when I hear about the disease in passing. As I mentioned above, if we're talking about sickle-cell, then definitely one of the first things I'll think about the disease itself is that most patients are of African descent - but in this context, I wasn't thinking about the disease on its own/for its own sake, but as a peripheral detail to something else entirely. I was reading everything in this book as it related to Shadow, so when I read that his mother had a debilitating disease, I was thinking about what it meant for him, not what it would have meant for/about his mother.