In the Roessler Liver 2 dataset, the mRNA expression of ALDH1B1, ALDH2, ALDH5A1, ALDH6A1, ALDH7A1, and ALDH9A1 was lower in HCC tissues compared with normal tissues with fold changes of 2.714, 2.185, 1.582, 3.481, 1.651, and 1.520 (p = 4.66E-52, 5.01E-61, 6.52E-21, 7.34E-57, 1.09E-18, 2.81E-29), respectively. This evidence concerns the gene ALDH9A1 and hepatocellular carcinoma.