The objective of this book is to review the impact of genetic variation on risk of human disease at the different major levels of organization: cells, individuals, families, and populations. The volume begins with a discussion of sources and rates of mutation which ultimately give rise to the vast amount of extant genetic variation. This is followed by presentations of current understanding of how genetic variation is maintained within and among populations. The volume ends with discussions of the implications of such variation for understanding the evolution of our species. This collection...