| A type of developmental and epileptic encephalopathy caused by biallelic variants in the PNPO gene, part of the lysine degradation pathway. Onset of seizures is usually shortly after birth or with intrauterine convulsions. Seizures are drug-resistant and frequent (often evolving to status epilepticus) but rapidly responding to pyridoxal-5'-phosphate. There are variable seizure types including focal/multifocal seizures, tonic seizures, clonic seizures, tonic-clonic seizures, epileptic spasms and multifocal myoclonus affecting limbs, trunk, eyes, and facial muscles. Infants may appear hyperkinetic, distressed, irritable and agitated. Infants may be acidotic and hypotonic. Cirrhosis of the liver has been reported. EEG is abnormal with slowing and focal/multifocal discharges or burst suppression pattern. The biomarker pyridoxal−5-phosphate is low in cerebrospinal fluid. |
