The KEGG pathway analysis illustrated that APOL4 was associated with the staphylococcus aureus infection, intestinal immune network of IgA production, leishmaniasis, autoimmune thyroid disease, allograft rejection, asthma, phagosome, systemic lupus erythematosus, toxoplasmosis, hematopoietic cell lineage, herpes simplex infection, type I diabetes mellitus, inflammatory bowel disease, pertussis, tuberculosis, antigen processing and presentation, DNA replication, and cytokine–cytokine receptor interaction in gliomas (Figure 6D). Here, APOL4 is linked to central nervous system cancer.