Enrichment analysis of the KEGG pathway revealed that downregulated differentially expressed genes were associated with the p53 signaling pathway, colorectal cancer, IL-17 signaling pathway, apoptosis, measles, cholesterol metabolism, Epstein–Barr virus infection, platinum drug resistance, small cell lung cancer and were related to toxoplasmosis. The gene discussed is IL17A; the disease is small cell lung carcinoma.