Department of Computer Sciences, University of Torino, C.so Svizzera 185, 10149 Torino, Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Department of Translational Medicine, University of Piemonte Orientale Avogadro, Novara, Unit of Cancer Epidemiology, Department of Medical Sciences, University of Turin, Turin, Department of Computational and Quantitative Biology, UMR 7238 CNRS - Université Pierre et Marie Curie, Paris, France and Department of Mathematics and Computer Science, University of Udine, Italy Department of Computer Sciences, University of Torino, C.so Svizzera 185, 10149 Torino, Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Department of Translational Medicine, University of Piemonte Orientale Avogadro, Novara, Unit of Cancer Epidemiology, Department of Medical Sciences, University of Turin, Turin, Department of Computational and Quantitative Biology, UMR 7238 CNRS - Université Pierre et Marie Curie, Paris, France and Department of Mathematics and Computer Science, University of Udine, Italy.