Typical and atypical phenotypes of PNPO deficiency with elevated CSF and plasma pyridoxamine on treatment

Abstract

Pyridox(am)ine phosphate oxidase (PNPO) deficiency causes severe early infantile epileptic encephalopathy and has been characterized as responding to pyridoxal-5′-phosphate but not to pyridoxine. Two males with PNPO deficiency and novel PNPO mutations are reported and their clinical, metabolic, and video-electroencephalographic (EEG) findings described. The first child showed electro-clinical responses to pyridoxine and deterioration when pyridoxine was withheld. At last review, he has well-controlled epilepsy with pyridoxal-5′-phosphate monotherapy and an autism spectrum disorder. The second child had a perinatal middle cerebral artery infarct and a myoclonic encephalopathy. He failed to re..