MAOA and cholangiocarcinoma: The next highlighted mRNAs, ADH5 (encodes alcohol dehydrogenase class III), AKR1B10 (encodes aldo-keto reductase 1 B10), AKR7A2 (encodes aldo-keto reductase family 7 member 2), ALDH1A1 (encodes aldehyde dehydrogenase 1A1), EPHX1 (encodes microsomal epoxide hydrolase), EPHX2 (encodes soluble epoxide hydrolase), MAOA (encodes monoamine oxidase A), and PTGS1 (encodes prostaglandin-endoperoxide synthase 1), are silenced at all clinical stages compared to CC (Table 2).