The science of genetics is perceived to offer hope that a large number of the 3,000 inherited diseases which afflict human beings may be prevented or controlled. This document addresses some of the advances that have been made in this field. It includes an introduction and sections on: "The Beginning of Human Genetics"; "Unlocking the Secrets of DNA"; "The Development of Recombinant DNA Techniques"; "A New Understanding of Sickle-Cell Disease and Other Blood Disorders"; "How to Use DNA Fragments to Detect a Disease"; "How DNA Probes Find Their Match"; "Stalking the Most Elusive Genes"; "The Rapid Growth of Gene Mapping"; "Zeroing In on Cancer Genes"; "A Bank of Living Human Cells"; "GenBank: A National Database of Nucleic Acid Sequences"; and "The Promise of Genetic Therapy." A glossary of terms is also included. (TW)