The fourth, completely revised edition of this classic reference and textbook presents a cohesive and up-to-date exposition of the concepts, results, and problems underlying theory and practice in human and medical genetics. In the 10 years since the appearance of the third edition, many new insights have emerged for understanding the genetic basis of development and function in human health and disease. Human genetics, with its emphasis on molecular concepts and techniques, has become a key discipline in medicine and the biomedical sciences. The fourth edition has been extensively expanded by new chapters on timely topics such as epigenetics, pharmacogenetics, gene therapy, cloning, and genetic epidemiology, and databases for basic and clinical genetics. In addition a multi/chapter section giving an overview on the main model organisms (mouse, dog, worm, fly, fish) used in human genetics research has been introduced. This book will be of interest to human and medical geneticists, scientists in all biomedical sciences, physicians and epidemiologists, as well as to graduate and postgraduate students who desire to learn the fundamentals of this fascinating field.