HAAO and esophageal squamous cell carcinoma: Then, 28 DE-TrpGs were obtained by overlapping the 6,029 DEGs and 66 TrpGs (Figures 2B, C), which contained eight upregulated (STAT1, IL4I1, TDO2, NMNAT3, KMO, IDO1, OGDHL, and ACAT2) and 20 downregulated DE-TrpGs (ALDH9A1, ALDH3A2, ADH1B, AOX1, MAOA, ECHS1, ALDH2, ACAT1, HAAO, ALDH7A1, HADHA, MAOB, AKR1A1, CYP4X1, INMT, CYP2U1, CAT, HADH, NMNAT1, and UGT2B11) between ESCC and normal samples (Figure 2B).