C3 and rheumatoid arthritis: In addition, “bone inflammation disease” and “rheumatoid arthritis” ontologies were highly enriched in C3 regions (Fig. 2e), confirming that C3 regions represent an RA signature, for example, IL-1B [21] and JAK1 [22], which are essential for proinflammatory signal transduction and upregulated in RA patients (Additional file 1: Figure S3a).