With Tay-Sachs, cystic fibrosis, and sickle cell disease as a powerful backdrop, the authors reveal how these maladies -- freighted with contentious ethnic and racial meanings for many Americans -- became topics of biological fascination and crucibles of social debate. They unveil a complex story: about different kinds of suffering and faith, about unequal access to the promises and perils of modern medicine, and about how Americans consume innovation and how they come to believe in, or resist, the notion of imminent medical breakthroughs.