This project will develop ethical guidance for presymptomatic testing for autosomal dominant, late onset diseases for which genetic probes are available (familial Alzheimer disease, amyotrophic lateral sclerosis, Huntington disease, myotonic dystrophy, neurofibromatosis, adult polycystic kidney disease and retinitis pigmentosa). Our six-member working group offers expertise in genetic counseling, clinical medical ethics, genetic research, law, ethics and communication. We will collect and analyze case studies, beginning with Indiana University's extensive experience with Huntington disease (HD). Experience with HD research and presymptomatic testing provides a unique and informative historical model. Co-PI Kimberly A. Quaid will visit selected testing centers, and we will solicit supplementary cases from major centers that offer testing for diseases of interest. We will define the full range of ethical problems presented by presymptomatic testing for these disorders, and we will explore the salient questions from the varied perspectives represented by the working group, considering ethical principles (autonomy, beneficence, justice); clinical practicality; administrative feasibility; changing research findings; religious beliefs and institutions; and political, cultural and economic contexts. Consultants P. Michael Conneally, Robert Burt, Albert Jonsen and Thomas Murray will read drafts of our cases, analyses and guidelines and provide regular feedback on our work throughout the project. In addition, we will solicit input from genetic counselors and others experienced with presymptomatic testing, and we will invite patients and families at risk to review our materials in progress to assess their sensitivity, adequacy and feasibility. Our final product, a book published by Indiana University Press, will include guidelines for presymptomatic testing of autosomal dominant, late onset disorders; annotated cases; and the description of a method for resolving ethical issues our guidelines do not address directly.