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.

Asperger's syndrome, X-linked mental retardation (MRX23), and chronic vocal tic disorder.

Pervasive developmental disorders are severe disorders of development with no consistent neurobiologic etiology and most often an idiopathic etiology. We report a 12-year-old male who met criteria for a pervasive developmental disorder (Asperger's syndrome) and a chronic tic disorder. The child also has an X-linked cognitive impairment (MRX23). The presence of tic symptomatology, pervasive developmental disorder, and fragile X syndrome has previously been reported. Since no singular etiology for Asperger's syndrome has been found, the possibility of other cases of Asperger's syndrome occurring with concurrent abnormalities on the X chromosome should be considered by clinicians, especially if tic symptomatology is present.