Table 1.

Mouse mutants for enzymes catalyzing conversion of retinol to retinoic acid (RA).

Gene	Official gene name	Enzyme name and activity with retinoids	Major defects observed in null mutants
Adh1	Adh1	class I alcohol dehydrogenase oxidation of retinol to retinaldehyde	non-lethal; adults fertile; hypersensitive to vitamin A toxicity due to reduced ability to clear excess retinol; increased retinyl esters
Adh3	Adh5	class III alcohol dehydrogenase oxidation of retinol to retinaldehyde	non-lethal; adults fertile; reduced postnatal survival during vitamin A deficiency
Adh4	Adh7	class IV alcohol dehydrogenase oxidation of retinol to retinaldehyde	non-lethal; adults fertile; reduced postnatal survival during vitamin A deficiency
Rdh1	Rdh1	retinol dehydrogenase-1 oxidation of retinol to retinaldehyde	non-lethal; adults fertile; increased body weight, adipose tissue, and retinyl ester levels
Rdh10	Rdh10	retinol dehydrogenase-10 oxidation of retinol to retinaldehyde	lethal at E13.5; craniofacial defects; small forelimbs
Raldh1	Aldh1a1	retinaldehyde dehydrogenase-1 oxidation of retinaldehyde to RA	non-lethal; adults fertile; hypersensitive to vitamin A toxicity due to reduced ability to clear excess retinaldehyde; protects against obesity in adult
Raldh2	Aldh1a2	retinaldehyde dehydrogenase-2 oxidation of retinaldehyde to RA	lethal at E9.5; failure in embryonic turning due to somite defect; enlarged heart; forelimb field absent; posterior hindbrain absent; posterior foregut absent
Raldh3	Aldh1a3	retinaldehyde dehydrogenase-3 oxidation of retinaldehyde to RA	lethal at birth; blockage of nasal passages; mild perioptic mesenchyme defect (more severe in Raldh1;Raldh3 double knockout); forebrain LGE/striatum defects