Fig. 4

Functional enrichment analysis of differentially expressed genes among three diseases. A Gene ontology (GO) functional enrichment analyze based on the hub genes. BP: biological process. CC: cellular components. MF: molecular function. B Network visualization of relationships of enriched functions and genes. C Protein–protein interaction (PPI) network of differentially expressed genes (DEGs) in AD brains. D PPI network of DEGs in PD brains. E PPI network of DEGs in MS brains