CD9 and inflammatory bowel disease: More interestingly, among the risk genes associated with IBD/UC, we observed that some genes (such as PTGS2, TNFAIP8, TNFAIP6, and CD9) were mostly upregulated in the MCI group, while other genes (such as HLA-DR, CD74, IFIH1, and ISG15) were only found upregulated in the MC group.