Pyridoxine-Responsive Seizures in Pyridoxamine Phosphate Oxidase Deficiency: Case Report and Review of the Literature

Abstract

Pyridoxamine 5-phosphate oxidase (PNPO) deficiency results in a block in the final step of producing pyridoxal 5’- phosphate. This is expected to result in neuronal cell dysfunction that leads to the early neonatal encephalopathy and intractable seizures that are theorized to be resistant to pyridoxine and responsive to pyridoxal 5’-phosphate. As a matter of fact, the lack of response of the intractable seizures to high dose supplementation with pyridoxine is one of the main clinical clues for suspecting PNPO deficiency, although partial response can be observed. This is a case report of genetically confirmed PNPO deficiency that had complete response to high dose Intravenous and then oral pyridoxine after failure to control his seizures with of conventional anti-epileptic drugs. This case further supports the increasingly recognized phenotypic heterogeneity of PNPO deficiency and the potential pitfall of diagnosing pyridoxine responsive seizures proper related to ALDH7A1 (Aldehyde Dehydrogenase 7 family, member A1) pathogenic mutations solely on the bases of clinical response to pyridoxine.