Clinical applications of genetic testing: implications for the family physician.

Genetic testing may be applied in a variety of clinical situations, including preconception counseling, prenatal diagnosis and postnatal determination of genetic predisposition to disease. The family physician needs to become familiar with the full range of genetic testing possibilities in all phases of the human life cycle. Cystic fibrosis, Huntington's disease and cancer are three diseases for which genetic testing has become a reality, and they serve to illustrate the clinical and ethical dilemmas that arise with this type of testing.