the principles of genetics and genetic counseling, including the ethical, legal, and social issues in genetic testing (see Chapters 4, 6, and 8).

The availability of presymptomatic testing for Mendelian disorders and the possibility of predispositional testing for complex disorders, such as cancers and heart disease, raise unique issues not evident in genetic testing of newborns or for reproductive planning, particularly pertaining to confidentiality—both inside and outside the family—and create new challenges for the physician-patient relationship. The availability of presymptomatic and predispositional testing provides an opportunity for physicians and patients to work toward prevention of disease. Thus, the goal of nondirective counseling (as discussed in Chapter 4), so crucial in genetic services pertaining to reproductive planning, may not always be appropriate when primary prevention or effective treatments are available. In such instances, it is considered appropriate for practitioners to give guidance to patients regarding the relevant interventions after fully explaining what is known about the potential benefits and harms of testing and of following such advice. In considering the use of presymptomatic tests, the committee recommends that the patient be the ultimate decision maker.

One concern about genetic tests for common, high-profile, complex disorders is that the potential number of such tests is likely to make them widely available; for-profit testing facilities may not be equipped to deal with the complexities of testing, interpretation, communication of results, and genetic counseling. The committee recommends strict guidelines for efficacy and standards for use to prevent premature introduction of this technology in disorders of late onset; this would be an appropriate role for the recommended national advisory body and its Working Group on Genetic Testing (see Chapter 9).

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