Multifunctional enzyme mediating important protective effects. Metabolizes betaine aldehyde to betaine, an important cellular osmolyte and methyl donor. Protects cells from oxidative stress by metabolizing a number of lipid peroxidation-derived aldehydes. Involved in lysine catabolism. Defects in ALDH7A1 are the cause of pyridoxine-dependent epilepsy (PDE). PDE is characterized by a combination of various seizure types. It usually occurs in the first hours of life and is unresponsive to standard anticonvulsants, responding only to immediate administration of pyridoxine hydrochloride. Belongs to the aldehyde dehydrogenase family. 3 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.