[1] Univ Cambridge, Dept Pathol, Cambridge CB2 1QP, England
[2] Univ Cambridge, Dept Oncol, Canc Genom Program, Cambridge, England
[3] Univ Cambridge, Dept Appl Math & Theoret Phys, Cambridge CB3 9EW, England
[4] Univ Lisbon, Fac Med, Inst Mol Med, P-1699 Lisbon, Portugal