FAHD2A is a mitochondrial tautomerase that catalyzes the conversion of enol-oxaloacetate to the physiological keto form of oxaloacetate 1. This enzymatic activity is essential for maintaining aerobic respiration efficiency by preventing succinate dehydrogenase inhibition, as enol-oxaloacetate acts as a potent inhibitor of this critical electron transport chain enzyme 1. FAHD2A belongs to a family of fumarylacetoacetate hydrolase domain-containing proteins with diverse metabolic functions 2. The enzyme is involved in oxaloacetate metabolic processes and exhibits oxaloacetate tautomerase activity, supporting mitochondrial energy metabolism. Beyond its canonical metabolic role, FAHD2A has been identified as a differentially expressed gene implicated in obesity-associated hepatocellular carcinoma pathogenesis 3, where it correlates with immune cell infiltration and immunotherapy response markers in HCC. Additionally, FAHD2A was identified as one of five discriminatory biomarkers in pancreatic cyst fluid that predict malignant transformation of intraductal papillary mucinous neoplasms, achieving strong predictive accuracy (AUC >0.75) 4. These findings suggest FAHD2A has dual roles: optimizing mitochondrial bioenergetics through oxaloacetate metabolism and potential involvement in cancer-related metabolic dysregulation.