1. M. T. Keating is at the Howard Hughes Medical Institute, Eccles Institute of Human Genetics, and the Cardiology Division, University of Utah, Salt Lake City, UT 84112, USA.
2. M. C. Sanguinetti is in the Eccles Program in Human Molecular Biology and Genetics and the Cardiology Division, University of Utah, Salt Lake City, UT 84112, USA.