Pyridoxine dependent epilepsy: Seizure onset, seizure types and EEG features

Pyridoxine dependent epilepsy (PDE) is an autosomal recessively inherited disorder. It is caused by mutations in the ALDH7A1 gene (PDE-ALDH7A1) encoding the alpha-aminoadipic semialdehyde dehydrogenase enzyme in the lysine catabolic pathway. The alpha-aminoadipic semialdehyde dehydrogenase enzyme deficiency leads to accumulation of alpha-aminoadipic semialdehyde and piperidine 6-carboxylic acid, the latter inactivates pyridoxal-5-phosphate. The majority of the patients present with neonatal onset intractable seizures with a dramatic response to pyridoxine therapy. Later seizure onset up to 3 yr of age has been reported too. Generalized tonic-clonic seizures are the most common seizure type. The treatment of PDE consists of high dose pyridoxine supplementation therapy. Since the underlying genetic defect was identified in the lysine catabolic pathway, few patients were treated with lysine-restricted diet to decrease, likely neurotoxic, alpha-aminoadipic semialdehyde and piperidine 6-carboxylic acid accumulation in the central nervous system.