1. P. Baird is with the Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6T 1Z3 Canada.
2. J. Downie is with the Faculties of Law and Medicine, Dalhousie University, Halifax, NS, B3H 4H9 Canada.
3. J. Thompson is with the Department of Mathematics and Statistics, University of New Brunswick, Fredericton, NB, E3B 5A3 Canada.