| Title | Somatic variants in new candidate genes identified in focal cortical dysplasia type II |
| Authors | Zhang, Zhongbin Gao, Kai Liu, Qingzhu Zhou, Jiapeng Li, Xiyuan Lang, Na Liu, Ming Wang, Tianshuang Zhang, Jie Wang, Hui Dong, Ying Ji, Taoyun Wang, Shuang Liu, Xiaoyan Jiang, Yuwu Cai, Lixin Wu, Ye |
| Affiliation | Peking Univ, Hosp 1, Dept Pediat, Beijing, Peoples R China Peking Univ, Hosp 1, Pediat Epilepsy Ctr, Beijing, Peoples R China Hunan Normal Univ, Coll Life Sci, Changsha, Peoples R China Chinese Acad Sci, Inst Comp Technol, Beijing, Peoples R China Peking Univ, Hosp 1, Dept Pathol, Beijing, Peoples R China |
| Keywords | HOC TASK-FORCE MUTATIONS MTOR EPILEPSY RECRUITMENT PATHWAY MODELS |
| Issue Date | Apr-2020 |
| Publisher | EPILEPSIA |
| Abstract | Objective Focal cortical dysplasia type II (FCDII) is a malformation of cortex development commonly found in children with drug-resistant epilepsy. FCDII has been associated with somatic mutations in mammalian target of rapamycin (mTOR)-related pathway genes and an upregulation of mTOR. Somatic mutations were found in 10%-63% of FCDII samples; the frequency of the mutant allele was 0.93%-33.5%. This study aimed to find new candidate genes involved in FCDII. Methods We collected resected FCD lesions, perilesional brain tissues, and peripheral blood from 17 children with pathologically confirmed FCDII. We performed whole exome sequencing and followed a set of screening and analysis strategies to identify potentially deleterious somatic variants (PDSVs) in brain-expressed genes. We performed site-specific amplicon sequencing to validate the results. We also performed an in vitro functional study on an IRS1 variant. Results In six of 17 samples, we identified seven PDSVs in seven genes, including two frameshift variants and five missense variants. The frequencies of the variant allele were 1.29%-5.50%. The genes were MTOR, TSC2, IRS1, RAB6B, RALA, HTR6, and ZNF337. PDSVs in IRS1, RAB6B, ZNF337, RALA, and HTR6 had not been previously associated with FCD. In one lesion, two PDSVs were found in two genes. In a transfected cell line, we demonstrated that the c.1791dupG (identified in FCDII from Patient 1) led to a truncated IRS1 and significant mTOR hyperactivation compared to cells that carried wild-type IRS1. mTOR was also activated in FCDII tissue from Patient 1. Significance Seven PDSVs were identified in FCDII lesions in six of 17 children. Five variant genes had not been previously associated with cortical malformations. We demonstrated that the IRS1 variant led to mTOR hyperactivation in vitro. Although functional experiments are needed, the results provide evidence for novel candidate genes in the pathogenesis of FCDII. |
| URI | http://hdl.handle.net/20.500.11897/587282 |
| ISSN | 0013-9580 |
| DOI | 10.1111/epi.16481 |
| Indexed | SCI(E) |
| Appears in Collections: | 第一医院 |
