A scientific and medical revolution has crept up on us. Twenty-one million Americans are affected by 6,000 so-called rare and orphan diseases, many of which are primarily attributable to misspelled genes. And virtually all diseases have a significant hereditary component. Diabetes, heart disease, the common cancers, mental illness, asthma, arthritis, Alzheimer's disease, and more are having their secrets unlocked through DNA. Families that faced common problems, with-out hope, are now discovering a new world of understanding, treatment, and prevention. You owe it to yourself to learn about your DNA: how it woks, what it reveals, and the benefits and limits of this new knowledge. Book jacket.