RDH13 (retinol dehydrogenase 13) is a mitochondrial short-chain dehydrogenase/reductase localized to the outer side of the inner mitochondrial membrane 1. The enzyme preferentially catalyzes the reduction of all-trans-retinal to all-trans-retinol using NADPH as a cofactor, with significantly higher catalytic efficiency in the reductive direction 1. RDH13 exhibits broad tissue distribution, with particularly high expression in liver and eye tissues 1, and functions in retinal metabolism during eye photoreceptor development and retina formation 2. The enzyme lacks steroid-metabolizing activity, distinguishing it from related dehydrogenases 13. RDH13 appears to play a protective role against oxidative stress, particularly in mitochondria exposed to reactive retinaldehyde 1. In liver, Rdh13 deficiency attenuates carbon tetrachloride-induced hepatic injury by reducing expression of metabolic enzymes Spot14 and Cyp2e1 4. Clinically, RDH13 variants have been associated with multiple disease states: it was identified as a hub gene in ulcerative colitis carcinogenesis, showing significant downregulation in the transition to colorectal cancer 5, and variants were found to influence penetrance of Leber's hereditary optic neuropathy through cofactor metabolism pathways 6. Additionally, RDH13 haplotypes show genetic association with bilateral convergent strabismus with exophthalmos in cattle 7.