[P1-71] Novel Phenotypes of Pyridox(am)ine-5’-phosphate Oxidase Deficiency and High Prevalence of c.445_448del Mutation in Chinese Patients
PNPO deficiency is a rare autosomal recessive inherited disorder. Up to now, less than 50 cases were reported world-widely. For the first time, we report 4 Chinese patients diagnosed as PNPO deficiency genetically here. Of them, patient 1 and 2 were identical twin brothers, who were born at 35+5w gestation with asphyxia. Their seizures started within the first day and could not controlled by pyridoxine and PLP completely. Patient 3 presented seizures at his 5 months, responding well to pyridoxine. Seizures in patient 4 began at his 40 days and were controlled by valproic acid and topiramate for a few years. EEG showed atypical hypsarrhythmia or multifocal epileptiform discharges in 3 patients, and showed normality in patient 4. MRI showed nonspecific abnormality or normality. Blood metabolic screening showed multiple amino acids level abnormality in 3 patients. Urinary metabolic screening showed vanillic acid elevating prominently in the twins. Genetic analysis revealed 5 mutations of PNPO, and 3 of them were novel. The mutation c.445_448del was carried by the siblings and patient 4. Psychomotor development were severe delay in 3 patients and borderline to mild delay in patient 3. In conclusion, the novel clinical characteristics here, including typical presentations but incomplete response to pyridoxine and PLP, later-onset seizures response well to pyridoxine, and seizures controlled by one or two kinds of AEDs, expanded the phenotypes of this disease. And novel mutations found here expanded the genotypes. Further, the frameshift mutation c.445_448del might be high prevalence in PNPO deficiency in Chinese patients.