List of known ALDH enzymes annotated with substrate preference, genetics, and cellular localization, where known
| Enzyme . | Likely substrate . | Tissue expression . | Adult deficiency . | Localization . |
|---|---|---|---|---|
| ALDH1a1 | 9-Cis retinaldehyde, maybe all-trans. Cyclophosphamide metabolite | All tissues: adipose, thyroid, liver, astrocyte enriched | Healthy and resistant to obesity | Cytosol |
| ALDH1a2 | All-trans retinaldehyde only | Reproductive tissues and immune tissues | Healthy | Cytosol |
| ALDH1a3 | All-trans retinaldehyde | Prostate/salivary glands | Healthy | Cytosol |
| ALDH2 | Acetaldehyde | Liver | Alcohol aversion, neurological and motor function | Mitochondria |
| ALDH1L1 | 10-Formyl-THF | Liver | Unknown, likely lethal | Cytosol |
| ALDH1L2 | 10-Formyl-THF | Pancreas | Unknown, likely lethal | Mitochondria |
| ALDH1b1 | Acetaldehyde | All tissues | Increased steatosis | Mitochondria |
| ALDH3a1 | Long chain lipid aldehydes, UV-based decay products, oxazaphosphorines, smoking damage | Cornea, esophagus, stomach | Viable; predisposed to cataracts | Cytosol |
| ALDH3a2 | Long chain lipid aldehydes | All tissues | Sjogren-Larsson syndrome | Cytosol |
| ALDH3b1 | Long chain lipid aldehydes | All tissues | Unknown | Cytosol |
| Aldh3b2 | Long chain lipid aldehydes | Breast, esophagus, skin | Unknown | Cytosol |
| ALDH4a1 | Glutamate semialdehyde | Kidney, liver | 4-hydroxybutyric aciduria | Mitochondria |
| ALDH5a1 | Succinate semialdehyde | All tissues | 4-hydroxybutyric aciduria | Mitochondria |
| ALDH6a1 | Methylmalonate semialdehyde | All tissues | Demyelination and methylmalonic aciduria | Mitochondria |
| ALDH7a1 | Aminoadipic semialdehyde | All tissues | Pyridoxine-dependent epilepsy | Mixed |
| ALDH8a1 | 2-Aminomuconate semialdehyde, potential 9-cis retinal | Kidney, liver | Unknown | Cytosol |
| ALDH9a1 | GABA | All tissues | Unknown | Cytosol |
| ALDH16a1 | Non-catalytic | Low basal expression | Unknown | Cytosol |
| ALDH18a1 | Pyrroline-5-carboxylate | All tissues | Cutis laxia | Mitochondria |
| Enzyme . | Likely substrate . | Tissue expression . | Adult deficiency . | Localization . |
|---|---|---|---|---|
| ALDH1a1 | 9-Cis retinaldehyde, maybe all-trans. Cyclophosphamide metabolite | All tissues: adipose, thyroid, liver, astrocyte enriched | Healthy and resistant to obesity | Cytosol |
| ALDH1a2 | All-trans retinaldehyde only | Reproductive tissues and immune tissues | Healthy | Cytosol |
| ALDH1a3 | All-trans retinaldehyde | Prostate/salivary glands | Healthy | Cytosol |
| ALDH2 | Acetaldehyde | Liver | Alcohol aversion, neurological and motor function | Mitochondria |
| ALDH1L1 | 10-Formyl-THF | Liver | Unknown, likely lethal | Cytosol |
| ALDH1L2 | 10-Formyl-THF | Pancreas | Unknown, likely lethal | Mitochondria |
| ALDH1b1 | Acetaldehyde | All tissues | Increased steatosis | Mitochondria |
| ALDH3a1 | Long chain lipid aldehydes, UV-based decay products, oxazaphosphorines, smoking damage | Cornea, esophagus, stomach | Viable; predisposed to cataracts | Cytosol |
| ALDH3a2 | Long chain lipid aldehydes | All tissues | Sjogren-Larsson syndrome | Cytosol |
| ALDH3b1 | Long chain lipid aldehydes | All tissues | Unknown | Cytosol |
| Aldh3b2 | Long chain lipid aldehydes | Breast, esophagus, skin | Unknown | Cytosol |
| ALDH4a1 | Glutamate semialdehyde | Kidney, liver | 4-hydroxybutyric aciduria | Mitochondria |
| ALDH5a1 | Succinate semialdehyde | All tissues | 4-hydroxybutyric aciduria | Mitochondria |
| ALDH6a1 | Methylmalonate semialdehyde | All tissues | Demyelination and methylmalonic aciduria | Mitochondria |
| ALDH7a1 | Aminoadipic semialdehyde | All tissues | Pyridoxine-dependent epilepsy | Mixed |
| ALDH8a1 | 2-Aminomuconate semialdehyde, potential 9-cis retinal | Kidney, liver | Unknown | Cytosol |
| ALDH9a1 | GABA | All tissues | Unknown | Cytosol |
| ALDH16a1 | Non-catalytic | Low basal expression | Unknown | Cytosol |
| ALDH18a1 | Pyrroline-5-carboxylate | All tissues | Cutis laxia | Mitochondria |