ALDH7A1 and hyperinsulinemic hypoglycemia, familial, 4: Pyridoxine-dependent epilepsy (PDE, OMIM: 266100) or ALDH7A1 deficiency (traditionally) and pyridox(am)ine-5′-phosphate oxidase (PNPO) deficiency (OMIM: 610090) are the most prevalent type (Stockler et al., 2011).