[Predictive medicine and its ethics].

Abstract

The concept of predictive medicine based on the detection of genetic markers for disease susceptibility stemmed from the finding that many diseases are associated with specific HLA alleles. This model suggested that similar associations probably existed with other genes located all along the human genome. The Human Specimen Study Center (HSSC) was created to assist in investigating this possibility and has contributed significantly to the knowledge contained in current genetic and physical human genome maps. Predictive medicine is intended not for patients but for healthy individuals, its goal being to determine whether their susceptibility to a specific disease is increased or not. Fetuses with evidence of disease are excluded from the province of predictive medicine, which can, however, determine whether a healthy fetus is at high risk for developing a disease in adolescence or adulthood. Predictive medicine is based on probabilities: it evaluates diseases susceptibility but cannot predict with 100% certainty that a specific disease will occur. Whereas many preventive interventions are directed at groups (e.g., immunization programs), predictive medicine is conducted on an individualized basis. For instance, glaucoma is a monogenic disease whose early detection can allow to prevent permanent loss of vision. The fruits of predictive medicine are expected to be greatest, however, in the polygenic multifactorial diseases that are prevalent in industrialized countries, such as diabetes mellitus, hypertension, myocardial infarction, hyperlipidemia, and arteriosclerosis. An ability to detect subjects who are susceptible to breast cancer would be extraordinarily useful, and may be a goal within reach since two breast cancer susceptibility genes have already been identified. Genes associated with increased susceptibility to colon cancer have also been reported. Predictive medicine raises a number of sensitive ethical issues. Individuals should be free to accept or decline disease susceptibility testing after having been fully informed. Confidentiality is vital. The results of susceptibility tests should not be made available to employers or insurance agencies. Susceptibility testing should be offered only if the disease requires a specific treatment or lifestyle modification. Unnecessary anxiety may be one of the main adverse effects of susceptibility testing. A large number of disease susceptibility or resistance genes will probably be identified in the near future, and this will inevitably have an impact on the way physicians approach their patients. Physicians in the XXIst century will spend an increasingly large proportion of their time counselling their patients on how to stay healthy. This trend can be expected to translate into a marked increase in life expectancy. Rather than seeking to add years to life, physicians will strive to add life to years.