Bilateral Periventricular Nodular Heterotopia With Megalencephaly

Bilateral periventricular nodular heterotopia is a neuronal migration disorder characterized by gray matter cellular rests in the periventricular regions. Megalencephaly has not been reported in children with bilateral periventricular nodular heterotopia. No other disorder with a similar phenotype has been reported. Here we report the case of a 5-year-old Japanese boy with bilateral periventricular nodular heterotopia and megalencephaly. Relative macrocephaly was evident at birth, and bilateral periventricular nodular heterotopia and megalencephaly were noted on magnetic resonance imaging (MRI). However, no hydrocephalus or indication of cerebral cortical dysplasia was seen. A mild intellectual disability was present, but the patient had no history of seizures. Genetic analysis revealed no mutation on the capillary sequences for FLNA, and no pathogenic abnormalities were evident on array comparative genomic hybridization. This case could represent a new disease entity: bilateral periventricular nodular heterotopia with megalencephaly.