<p>In the first step, AD, PD and HD susceptibility gene (sg) sets were collected and their intersection were defined as common sg. Meanwhile, common sg's first neighbors in the human protein-protein interaction network (hPPIN) was extracted to construct common gene first neighbor network (CFNN). Then, KEGG pathway enrichment analysis was applied to the nodes in CFNN to get shared pathways of AD, PD and HD, following by gene expression analysis to evaluate the found pathways. Finally, hierarchal clustering was applied to cluster the enriched pathways and indentify common modules in CFNN. RWR: random walk with restart.</p
