Aldehyde dehydrogenase 1A1 (ALDH1A1), an enzyme expressed by dopaminergic neurons for the detoxification of these neurons, is controlled by retinoic acid and plays a crucial role of aldehyde dehydrogenase enzymes in the survival of dopaminergic neurons by controlling the ALDH1A1 enzyme in PD (103). Here, ALDH1A1 is linked to Parkinson disease.