GSEA analysis adds more insight into the 23 ERBB2-related DEGs and primary immunodeficiency signaling pathway, showing that ERBB2-related DEGs associated with primary immunodeficiency were mainly down-regulated ERBB2-related DEGs, such as CD79A, CD19, CD3D, CD3E, CD8A, and CD4 (Figure 7B). The gene discussed is CD8A; the disease is inborn error of immunity.