Pyridoxine-dependent seizures associated with white matter abnormalities.

Pyridoxine-dependent seizures are a disorder of GABA metabolism probably due to a defective binding of pyridoxal phosphate coenzyme (PALP) with glutamate decarboxylase (GAD), the rate-limiting enzyme in GABA synthesis. The resulting GABA deficiency causes severe epilepsy in infancy. We report on a boy with seizures starting soon after birth, and only controlled by pyridoxine at pharmacological dosages. After two months without seizures, a CT scan showed hypodense white matter in frontal and occipital lobes suggestive of a retarded or defective myelination. We are not aware of other descriptions of such morphological abnormalities in a patient with this disorder.