This is an interesting and important paper using a systems biology approach to dissect the underlying mechanisms of disease. The authors comment on the surprising inclusion of immune related pathways in Alzheimer's disease. KEGG pathway analysis of the hundreds of genes involved in autism, bipolar disorder, schizophrenia, as well as in Alzheimer's disease, Parkinson's disease and multiple sclerosis (taken from both pre- and post GWAS studies) show that this is also the case in all these conditions. Pathogen defense and entry pathways are also well represented with toxoplasmosis heading the list in schizophrenia. Pathogens, as well as genes are implicated in all of these conditions and are a likely source of the immune activation that also occurs in each case. Genes and risk factors seem to be working together via these networks. These pathways and the genes and risk factors involved are available at PolygenicPathways http://www.polygenicpathw...