a1 Centre for Brain and Cognitive Development, Birkbeck College, University of London, London WC1E 7HX, United Kingdom. email@example.com http://www.cbcd.bbk.ac.uk/people/students/sam firstname.lastname@example.org http://www.psyc.bbk.ac.uk/research/DNL/personalpages/annette.html
We welcome network theory as a tool for modelling the multi-directional interactions that characterise disease. However, we feel that Cramer et al. have neglected one important aspect: how diseases change over developmental time. We discuss principles such as fan in, fan out, bottlenecks, and common pathways, and argue that modelling these developmental aspects can be vital, particularly in deriving properly targeted treatments.