[Clinical features of epilepsy in children with IRF2BPL gene variation]

Objective: To summarize the genotype and phenotype of epilepsy in patients with interferon regulatory factor 2 binding protein-like (IRF2BPL) gene variants. Methods: Data of 6 epilepsy patients with IRF2BPL gene variants seen from May 2017 to September 2020 in the Department of Pediatrics of Peking University First Hospital were retrospectively collected. The clinical characteristics and genetic test results were analyzed. Results: A total of 6 patients with IRF2BPL gene variants (1 boy and 5 girls) were identified. The age of seizure onset was from 3.5 to 7.0 months. Epileptic spasms were observed in 6 patients, tonic seizures and tonic-spasms were observed in 1 patient and focal seizure was observed in 1 patient. All 6 patients presented with developmental delay, 5 patients presented with hypotonia, and 2 patients presented with dysphagia. Microcephaly,nystagmus,chorea and athetosis were observed in 1 patient. The electroencephalography (EEG) showed slow background activity in 2 patients. Hypsarrhythmia was observed in all 6 patients. Focal epileptic discharges were observed in 2 patients. Epileptic spasms were monitored in all 6 patients. Focal seizure and tonic-spasm were monitored in 2 patients respectively. The brain magnetic resonance imaging (MRI) showed cerebral atrophy and dysplasia of the corpus callosum in 1 patient, delayed myelination in 2 patients and normal in 3 patients. Two patients had missense variants c.1280C>T/p.L474F and c.1420C>T/p.S427L, 3 patients had frameshift variants c.232delG/p.V78Sfs*73, c.244del/p.A82Pfs*70 and c.283-308del/p.Ala95Thrfs*29, 1 patient had non-frameshift deletion variant c.1453-c.1455delTTC/p.F485del, and all of the 6 cases had de novo variants. All patients were diagnosed with infantile spasms. The last follow-up age ranged from 1 year to 3.8 years. Four patients achieved seizure-free and 2 patients still had frequent seizures after the treatment with antiepileptic drugs (adrenocorticotropic hormone, topiramate, and vigabatrin). Conclusions: IRF2BPL gene variants are mainly de novo. The age of seizure onset is mainly in infancy, and epilepsy and developmental delay are the main clinical manifestations. Infantile spasm is the main phenotype, some patients have hypotonia and dysphagia. Cerebral atrophy can be observed in a few patients.