As the pace of change in molecular biology continues to increase, the effect of new technologies and their application to clinical practice is constantly being reassessed. In the new edition of this book, the author has completely revised the text to include these new developments and their implications. The book introduces non-specialist readers to the principles and scientific background which have provided insight into the study of human genes and their structure, activity, and role in normal and abnormal protein synthesis. This knowledge leads to clearer understanding of the molecular pathology of disease and to an awareness of potential applications to diagnosis and the development of therapeutic techniques. New applications for cancer, prenatal diagnosis, and gene therapy are dealt with, and the moral and ethical implications are fully discussed. For this new edition many of the illustrations have been redrawn and revised, and numerous new figures are included to clarify the discussion and aid the reader.