Genetic susceptibility testing for neurodegenerative diseases: ethical and practice issues.

As the genetics of neurodegenerative disease become better understood, opportunities for genetic susceptibility testing for at-risk individuals will increase. Such testing raises important ethical and practice issues related to test access, informed consent, risk estimation and communication, return of results, and policies to prevent genetic discrimination. The advent of direct-to-consumer genetic susceptibility testing for various neurodegenerative disorders (including Alzheimer's disease (AD), Parkinson's disease, and certain prion diseases) means that ethical and practical challenges must be faced not only in traditional research and clinical settings, but also in broader society. This review addresses several topics relevant to the development and implementation of genetic susceptibility tests across research, clinical, and consumer settings; these include appropriate indications for testing, the implications of different methods for disclosing test results, clinical versus personal utility of risk information, psychological and behavioral responses to test results, testing of minors, genetic discrimination, and ethical dilemmas posed by whole-genome sequencing. We also identify future areas of likely growth in the field, including pharmacogenomics and genetic screening for individuals considering or engaged in activities that pose elevated risk of brain injury (e.g., football players, military personnel). APOE gene testing for risk of Alzheimer's disease is used throughout as an instructive case example, drawing upon the authors' experience as investigators in a series of multisite randomized clinical trials that have examined the impact of disclosing APOE genotype status to interested individuals (e.g., first-degree relatives of AD patients, persons with mild cognitive impairment).