Clinical genetics is one of the most rapidly advancing fields in medicine. Spectacular progress has been achieved in this century with unravelling of the entire draft sequence of the human genome. A major contribution of these advances has been in diagnosis, management and prenatal diagnosis of genetic disorders as treatment in most cases is difficult or impossible and where available beyond the means of most families. Genetic technology is advancing rapidly, bringing new, safer and more sensitive ways to diagnose genetic conditions pre- and postnatally. These advances will bring about profound changes in the way we deliver obstetric services to women and their families. Diagnosing a genetic disorder not only allows for disease-specific management options but also has implications for the affected individual's entire family. Hence, a working understanding of the underlying concepts of genetic disease is important for all practicing clinicians. Although it is impossible to know all aspects of clinical and molecular genetics, basic knowledge of certain topics is a must for all practicing obstetrician/gynecologists.