1. Division of Neurology, University of Washington, Seattle, WA 98195.
2. Division of Neurology, Veterans Administration Medical Center, Seattle 98108.
3. Center for Inherited Diseases, University of Washington, Seattle 98195.
4. Department of Pathology, University of Washington, Seattle 98195.
5. Department of Biostatistics, University of Michigan, Ann Arbor, 48109.
6. Geriatric Research Education and Clinical Center, American Lake Veterans Administration Medical Center, Tacoma, WA 98493.
7. Center for Molecular Biology, University of Heidelberg, Heidelberg, Federal Republic of Germany.