1. Department of Medical Informatics, University of Utah Medical Center, Salt Lake City, UT 84132.
2. Department of Pediatrics, University of Utah Medical Center, Salt Lake City, UT 84132.
3. Department of Ophthalmology, University of Utah Medical Center, Salt Lake City, UT 84132.
4. Department of Medical Genetics, University of Toronto, Toronto, Canada, M5S 1AB.
5. Departments of Microbiology and Immunology and of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461.
6. Howard Hughes Medical Institute and Department of Human Genetics, University of Utah Medical Center, Salt Lake City, UT 84132.