A 15-Year Follow-Up of a Boy With Pyridoxine (Vitamin B6)-Dependent Seizures With Autism, Breath Holding, and Severe Mental Retardation

Pyridoxine (vitamin B6) (2q31) dependency is a rare autosomal-recessive disorder that causes a severe seizure disorder of prenatal or neonatal onset. The abnormality appears to inhibit the binding of vitamin B6 to the enzyme glutamic acid decarboxylase-1, which is needed for the biosynthesis of gamma-aminobutyric acid (GABA). Most patients with pyridoxine-dependent seizures require lifelong treatment with pyridoxine. The full range of associated symptomatology is unknown since fewer than 100 cases have been reported. A majority of cases are mentally retarded. We report a 15-year-old boy with pyridoxine-dependent seizures, nonpyridoxine-dependent seizures, severe mental retardation, autistic disorder, aerophagia, breath holding, and self-injury. This complex outcome should alert clinicians to the wide range of neuropsychiatric outcomes associated with this disorder.