It has become increasingly clear over the past several years that Polycystic Ovary Syndrome (PCOS) is a complex genetic disease resulting from the interaction of susceptibility genes and environmental factors. This book includes the latest diagnostic criteria for PCOS and comprises the most up-to-date information about the genetic features and pathogenesis of PCOS. It critically reviews the methodological approaches and the evidence for various PCOS susceptibility genes. The book also discusses additional familial phenotypes of PCOS and their potential genetic basis. This expert opinion remains critical to guiding practice in PCOS because sufficient data for evidence-based guidelines remains scarce.