Implications of predictive testing in neurodegenerative disorders

Nowadays, healthy individuals are able to undergo genetic testing in order to find out whether or not they will develop defined genetic conditions in the future. Predictive testing, which is commonly performed in cancer genetics, is also available for an increasing number of neurodegenerative disorders. Receiving the news that one will develop a serious and, in the majority of cases, currently non-treatable disease is a life-changing event. The outcome of such predictive testing is therefore full of implications for the individual's psychological well-being and for his or her present and future life. Psychological implications of predictive testing differ with the nature of the result obtained. Independently of the outcome, individuals need time to adjust to the knowledge of their genetic status. Awareness of risk status has a profound impact not only on individuals but also on their families. Members of the family may see their risk change after an individual has had predictive testing. Offspring are among the first concerned by a predictive test outcome. After receiving an unfavourable result, some individuals may ask for predictive testing for their children. However, for an adult onset condition the option to be tested should be left to the children's own discretion once they are able to make an informed decision. It is the individual's responsibility to share the outcome of their test with at-risk relatives but not with other third parties such as employers and insurance companies. Professionals should help identifying the at-risk relatives and emphasise the importance of disclosing genetic information to them. The ethical principles of autonomy and confidentiality deserve a particular attention in the field of predictive testing. A careful forethought before undergoing a genetic test is essential. By providing information and decision-making support, genetic counselling plays an important role in this contemplation process. It is internationally accepted that predictive testing should be performed following structured guidelines. The latter have been inspired from the predictive testing protocol for Huntington's disease (HD) proposed by the UK HD Consortium. It is recommended that the individual attends several counselling sessions before undergoing the test in order to allow adequate preparation. Follow-up and support should be planned in advance and other counselling sessions should be available if the individual asks for it. A multidisciplinary approach to predictive testing which takes the medical, social and psychological aspects of the diseases into account is essential for good practice. A collaboration with neurologists and psychiatrists is therefore essential. Published reports have shown that individuals have gained from this apparently complex procedure. Individuals who have had extensive pre-test counselling cope better with the test results. Data have shown that pre-test emotional state is a predictor of the individual's post-test reaction and therefore the test protocol should include a pre-test assessment of the emotional state of the individual. The new Swiss law (Loi sur l'Analyse Genetique Humaine, LAGH) requires that individuals undergoing predictive testing have access to proper genetic counselling.