The core region of Module_1 mainly consisted of aldehyde dehydrogenase (ALDH) superfamily members, of which multiple genes, such as ALDH7A1, ALDH2, ALDH9A1, ALDH3A2, ALDH1A3 and ALDH3B2, were differentially expressed in ESCC (Figure 5B). The gene discussed is ALDH9A1; the disease is esophageal squamous cell carcinoma.