The expression of MAOB, IL4I1, ALDH3A2, WARS2, HAAO, AANAT, IDO1, OGDH, EHHADH, AOC1, INMT, HADHA, ALDH9A1, ALDH2, ECHS1, AADAT, ALDH1B1, CAT, HADH, GCDH, MAOA, IDO2, TPH1, and CYP1B1 was higher in glioma than normal brain tissue samples. Here, HAAO is linked to glioma.