Pyridoxamine-5'-phosphate oxidase (PNPO) deficiency is a rare autosomal recessive disorder that causes intractable seizures that are not responsive to anticonvulsant drugs and pyridoxine. Patients with this deficiency have very low concentrations of pyridoxal 5'-phosphate (PLP), leaving exogenous pyridoxal/PLP as the only source of the active cofactor. Clinically, this disease presents with neonatal epileptic encephalopathy with severe seizures which do not respond to anticonvulsant drugs or pyridoxine but shows a dramatic response to PLP. Pathogenic mutations in PNPO gene have been identified.
