1. Banting and Best Department of Medical Research, Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada.
2. Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal.
3. Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada.
4. Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
5. University of Cambridge, CRUK-Cambridge Institute, Robinson Way, Cambridge CB2 0RE, UK.
6. Department of Computer Science, University of Toronto, Toronto, Ontario M5S 2E4, Canada.
7. Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
8. Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge CB10 1SA, UK.