An idealized systems medical approach to personalized treatment. (a) All factors that influence a disease can potentially be described by networks. For example, symptoms and signs that tend to co-occur can be linked and form a module that corresponds to a disease (pink oval). That module may be linked to underlying modular protein changes (blue oval). Similarly, the disease module may be linked to co-occurring environmental factors (green oval). (b) Each of the modules in (a) can be further divided to represent different sublayers, from which (c) predictive markers from the different sublayers can be identified, and used for (d) personalized treatment. MLDM, multilayer disease module; nc-RNA, noncoding RNA; PPI, protein-protein interaction; SNPs, single-nucleotide polymorphisms.