Since the first edition of this highly acclaimed text was published in 1992, much new knowledge has been gained about the role of genetic factors in common adult disease, and we now have a better understanding of the molecular processes involved in genetic susceptibility and disease mechanisms. The Second Edition fully incorporates these advances. The entire book has been updated and twelve new chapters have been added. Most of these chapters deal with diseases such as gallstones, osteoporosis, osteoarthrits, skin cancer, other common skin diseases, prostate cancer and migraine headaches that are seen by all physicians. Others address the genetic and molecular basis of spondyloarthropathies, lupus, hemochromatosis, IgA deficiency, mental retardation, hearing loss, and the role of mitochondrial variation in adult diseases. Chapters on the evolution of human genetic disease and on animal models add important background on the complexities of these diseases. Unique clinical applications of genetics to common diseases are covered in additional new chapters on genetic counselling, pharmacogenetics, and the genetic consequences of modern therapeutics.