1. T. M. Olson and Y.-S. Tai, Department of Pediatrics, Division of Cardiology, University of Utah Health Sciences Center, Salt Lake City, UT 84112, USA.
2. V. V. Michels, Department of Medical Genetics, Mayo Clinic/Foundation, Rochester, MN 55905, USA.
3. S. N. Thibodeau, Department of Laboratory Medicine and Pathology, Mayo Clinic/Foundation, Rochester, MN 55905, USA.
4. M. T. Keating, Howard Hughes Medical Institute, Eccles Institute of Human Genetics, Department of Human Genetics, and Department of Medicine, University of Utah Health Sciences Center, Salt Lake City, UT 84112, USA.