1. With sickle-cell disease, red blood cells look like bananas rather than, as is normal, round cushions.

rather than 而不是

What made you choose the one rather than the other?

你怎么选了这个而不是那个？

2. Other mutations are known to lessen sickle-cell’s impact, but most knowledge of genetic modifiers is particular to Europeans.

known to 已知

It must be stated that this illness is one of the most complex conditions known to man.

必须声明，这种疾病是人类已知的最为复杂的疾病之一lybeeqq-.S!#A^。