Hepatocellular carcinoma is a special case because the expression of many ALDH subtypes, including ALDH1A1, ALDH1L1, ALDH2, ALDH3A2, ALDH4A1, ALDH7A1, and ALDH9A1, is relatively high in this cancer. This evidence concerns the gene ALDH1A1 and hepatocellular carcinoma.