Thirty years ago when the senior author entered the field of genetics, obstetrician-gynecologists had little need for genetic principles as part of their training or practice. However, in three short decades, genetics has become an integral part of all aspects of women's health care. Molecular techniques have replaced culturing for infectious dis-eases, and the diagnosis and management of cervical disease is based on molecular as-sessment of human papillomavirus typing. Prenatal diagnosis has expanded from testing for chromosomal abnormalities and a few biochemical disorders to direct gene mutation testing for a host of genetic conditions. Screening for genetic diseases can now be done directly on fetal DNA circulating in the maternal blood stream, and represents the first population-wide application of genomics to clinical care. What was once a specialty focused on rare diseases, affecting very few patients, is now the basis for understanding who is pre-disposed to disease, how an individual will respond to therapy, and what cancer treatment is best, based on tumor profiles. The field is changing so rapidly that even those with specialized training in genetics have difficulty keeping up with the newest findings that have implication for patient care.
Our goal in creating this book is simple: to provide a basic text that can serve as the foundation for an OB/GYN resident, or practicing OB/GYN in the genetic principles that will allow them to integrate genetics into their practice, and allow them to interpret new literature through the lens of these basic principles. In the field of genetics, or genomics as it is currently described, no textbook can expect to be current. At the time of writing this manuscript, the number of disease-causing genes was over 4000, with more than 100,000 different mutations described in these 4000 genes. It is estimated over 300 new disease-causing mutations are being reported annually. We present broad principles we expect will provide the reader with the basic skill set necessary for what must be lifelong learning in the field of genomics. Our format is simple: we provide an introductory case scenario and base our discussion on how the case should be managed. It is our hope this approach can serve as the foundation for our reader to learn the genetic principles necessary to build the knowledge base required for good patient care.