C4BPB and sexually transmitted disease: Among YMSM with STI, 23 genes were significantly (padj<0.1) differentially expressed between YMSM with and without HIV (Fig 4B), six of which (DMBT1, C4BPA, C4BPB, ZNF132, CASP5, and TNIP3) were also among the 47 significant interaction genes.