According to one of the theories behind RLS, it's tied to a variation of the gene BTBD9, found in flies, but called dBTBD9. Scientists engineered flies to lack this gene and the insects were hit by a version of the syndrome. They moved more, and lost sleep. Which is one of the key complaints about RLS.
Scientists went on to further our understanding of how RLS functions by controlling dopamine in the brain and the iron balance of cells. Amazing how we look to flies to figure out ourselves instead.