[1] McGill Univ, Jewish Gen Hosp, Lady Davis Inst Med Res, Ctr Clin Epidemiol, Montreal, PQ H3A 0G4, Canada
[2] McGill Univ, Dept Med, Montreal, PQ H3A 0G4, Canada
[3] McGill Univ, Dept Human Genet, Montreal, PQ H3A 0G4, Canada
[4] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Div Gen Internal Med, Boston, MA 02115 USA
[5] Harvard Univ, Sch Med, Dept Med, Boston, MA 02115 USA
[6] McGill Univ, Dept Oncol Epidemiol Biostat & Occupat Hlth & Hum, Montreal, PQ H3A 0G4, Canada
[7] Kings Coll London, Dept Twin Res & Genet Epidemiol, London SE1 7EH, England