Interestingly, five hub genes (ICOS, SELL, MS4A1, CR2, and CCR7) also participated in those pathways, and ICOS was identified as a key molecule for subsequent validation and analysis based on its central node role in three pathways including CAMs, intestinal immune network for IgA production, and primary immunodeficiency. The gene discussed is MS4A1; the disease is inborn error of immunity.