[1] Princeton Univ, Lewis Sigler Inst Integrat Genom, Princeton, NJ 08544 USA
[2] Univ Toronto, Donnelly Ctr Cellular & Biomol Res, Banting & Best Dept Med Res, Toronto, ON M5S 3E1, Canada
[3] Univ Minnesota, Dept Comp Sci & Engn, Minneapolis, MN 55455 USA
[4] Univ Toronto, Dept Mol Genet, Toronto, ON M5S 3E1, Canada