Clinical phenotype and genetic analysis of BRWD3 gene variation related infantile epileptic spasm syndrome / 中华神经科杂志

ABSTRACT

Objective:To investigate the clinical phenotype and genetic characteristics of infantile epileptic spasm syndrome caused by BRWD3 gene mutation. Methods:Clinical data of a child with BRWD3 related infantile epileptic spasm syndrome who was admitted to Department of Pediatric Neurology of Linyi People′s Hospital on August 2, 2019 were collected and followed up, whole exome sequencing technology and Sanger sequencing were applied to verify the child and his parents, and the pathogenicity of mutation site was analyzed. The studies till June 2023 were searched with keywords of " BRWD3" in both English and Chinese databases of China National Knowledge Infrastructure, Wanfang, Online Mendelian Inheritance in Man, and PubMed. The clinical phenotype and genetic characteristics of patients with BRWD3 related epilepsy were summarized. Results:The patient was a 4 years and 4 months old boy, with a clinical phenotype including severe global development delay, focal seizures (the onset age was 4 months), epileptic spasm (the onset age was 6 months), autism, megacephaly, high forehead as well as hypsarrhythmia. The whole exome sequencing results showed a de novo and frameshift variation c.4318_4319del(p.Q1441Efs*20)(NM_153252) in the BRWD3 gene, and the variation was interpreted as pathogenic (PVS1+PS2+PM2) according to the American College of Medical Genetics and Genomics variant classification criteria and guidelines. A total of 7 English literature articles were retrieved reporting 16 cases of BRWD3 gene related epilepsy in children (including 1 case of infantile epileptic spasm syndrome), and there has been no report in China yet. Totally there were 17 cases of BRWD3 gene related epilepsy including this case. All the cases showed X chromosome dominant inheritance, of whom 15 cases showed minor variations, including 7 missense variations, 3 frameshift variations, 3 splicing variations, 2 nonsense variations, and the remaining 2 cases showed large segment deletions. A total of 15 different variants were found. The phenotypes of the 17 patients mainly included epileptic seizures (17/17), intellectual disability (10/17), motor development disorder (7/17), speech impairment (9/17), megacephaly (8/17), facial malformation (8/17), autism (4/17) and hypotonia (4/17). The common seizure types were found to be focal seizures, occasionally epileptic spasm seizures and tonic seizures. Conclusions:BRWD3 gene variation related epilepsy is an X chromosome dominant genetic disease with a wide clinical phenotype spectrum. BRWD3 gene mutation c.4318_4319del(p.Q1441Efs *20) could cause infantile epileptic spasm syndrome, manifested as severe global developmental delay, epileptic spasm, focal seizures, autism, craniofacial malformation and hypsarrhythmia. This research enriches BRWD3 gene mutation spectrum.