In addition, univariate Cox analysis was performed to identify the protective factors for ESCC: 10 protective factors (MAOA, INMT, ALDH7A1, AOX1, AKR1A1, ALDH9A1, ACAT1, HAAO, ALDH2, and HADH) were identified in the GSE121931 cohort (Figure 5C). The gene discussed is HAAO; the disease is esophageal squamous cell carcinoma.