Non-mendelian genetics

The rapidly changing world of perinatal genetics can present a challenge for obstetrics and gynecology providers. As more information, screening, and testing options have become available, patients are able to learn more about the risk of transmission of genetic disorders to their children. An essential principle of Mendelian inheritance, which classically includes autosomal dominant, autosomal recessive, and X-linked inheritance, is that once a mutation occurs, that exact and predictable variant will be passed from parent to offspring. However, we now know that not all disorders follow strict Mendelian inheritance. Perinatal genetic counseling and testing are even more challenging when inheritance patterns are complex. This chapter will cover non-Mendelian patterns of inheritance, including, in particular, those that are important in perinatal, neonatal, and gynecologic settings.