The science of genetics is revolutionizing the practice of medicine. Using genetics, drugs are being developed from bacteria, viruses are carrying new coding instructions into human bodies, cancer treatments are targeting the specific gene mutations from which the disease arises, and individual genetic profiles are determining both the risk of and treatments for some diseases. From diagnosing genetic disorders prenatally to replacing faulty genes with normal ones, medical researchers are paving the way to a future in which previously fatal diseases can be eliminated.