This text fuses science and medicine, clearly demonstrating the clinical relevance of microbiology, and the way in which this rapidly emerging discipline is beginning to reshape the way disease is investigated and how patients are screened, diagnosed and treated. The first part of the book summarises knowledge of basic cell biology with clear and lucid descriptions of how genes work and how the study of human variation and heredity is applied to medical practice. A detailed analysis of Heamophilia A provides a paradigm for the use of molecular biology in the study and treatment of inherited disease. The second section takes the reader through the systematic approaches to studying genes, and provides an entry point for clinicians and researchers who wish to investigate a disease themselves or interpret the experiments of others. The third section shows how molecular biology has been used in medical research to investigate the mechanisms of common diseases; and the final section identifies areas where molecular biology has been used to diagnose and treat disease. It looks at the principles and practice of gene therapy and the design and production of recombinant products for medical use. The book closes with a description of how molecular biology has impinged upon prenatal diagnosis, and the ethical considerations which this raises.