Studies by Narayanan et al. and Liu et al. disclosed that diabetes-induced upregulation of spermine oxidase (SMOX) leads to the oxidation of spermine to spermidine, resulting in the increase in reactive aldehydes and H2O2, which are further converted to acrolein, resulting in retinal neuronal damage and dysfunction [129, 130]. The gene discussed is SMOX; the disease is diabetes mellitus.