2. Academic Validation
  3. Somatic Mutations in TSC1 and TSC2 Cause Focal Cortical Dysplasia

Somatic Mutations in TSC1 and TSC2 Cause Focal Cortical Dysplasia

  • Am J Hum Genet. 2017 Mar 2;100(3):454-472. doi: 10.1016/j.ajhg.2017.01.030.
Jae Seok Lim 1,  Ramu Gopalappa 2,  Se Hoon Kim 3,  Suresh Ramakrishna 4,  Minji Lee 5,  Woo-Il Kim 1,  Junho Kim 6,  Sang Min Park 1,  Junehawk Lee 7,  Jung-Hwa Oh 8,  Heung Dong Kim 9,  Chang-Hwan Park 4,  Joon Soo Lee 9,  Sangwoo Kim 6,  Dong Seok Kim 10,  Jung Min Han 11,  Hoon-Chul Kang 9,  Hyongbum Henry Kim 12,  Jeong Ho Lee 13
Affiliations

Affiliations

  • 1 Brain Korea 21 Plus Project, Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science & Technology, Daejeon 34141, South Korea.
  • 2 Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, South Korea; Brain Korea 21 Plus Project for Medical Sciences, Graduate Program of Nano Science and Technology, Department of Pharmacology, Yonsei University College of Medicine, Seoul 03722, South Korea.
  • 3 Department of Pathology, Yonsei University College of Medicine, Seoul 03722, South Korea.
  • 4 Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, South Korea.
  • 5 Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul 03722, South Korea.
  • 6 Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 03722, South Korea.
  • 7 Biomedical HPC Technology Research Center, Korea Institute of Science and Technology Information, Daejeon 34141, South Korea.
  • 8 Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon 34114, South Korea.
  • 9 Division of Pediatric Neurology, Department of Pediatrics, Pediatric Epilepsy Clinics, Severance Children's Hospital, Epilepsy Research Institute, Yonsei University College of Medicine, Seoul 03722, South Korea.
  • 10 Pediatric Neurosurgery, Severance Children's Hospital, Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, South Korea.
  • 11 Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul 03722, South Korea; College of Pharmacy, Yonsei University, Seoul 03722, South Korea.
  • 12 Brain Korea 21 Plus Project for Medical Sciences, Graduate Program of Nano Science and Technology, Department of Pharmacology, Yonsei University College of Medicine, Seoul 03722, South Korea; Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 03722, South Korea; Center for Nanomedicine, Institute for Basic Science, Yonsei University, Seoul 03722, South Korea. Electronic address: hkim1@yuhs.ac.
  • 13 Brain Korea 21 Plus Project, Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science & Technology, Daejeon 34141, South Korea. Electronic address: jhlee4246@kaist.ac.kr.
PMID: 28215400 DOI: 10.1016/j.ajhg.2017.01.030
Abstract

Focal cortical dysplasia (FCD) is a major cause of the sporadic form of intractable focal epilepsies that require surgical treatment. It has recently been reported that brain somatic mutations in mTOR account for 15%-25% of FCD type II (FCDII), characterized by cortical dyslamination and dysmorphic neurons. However, the genetic etiologies of FCDII-affected individuals who lack the mTOR mutation remain unclear. Here, we performed deep hybrid capture and amplicon Sequencing (read depth of 100×-20,012×) of five important mTOR pathway genes-PIK3CA, PIK3R2, Akt3, TSC1, and TSC2-by using paired brain and saliva samples from 40 FCDII individuals negative for mTOR mutations. We found that 5 of 40 individuals (12.5%) had brain somatic mutations in TSC1 (c.64C>T [p.Arg22Trp] and c.610C>T [p.Arg204Cys]) and TSC2 (c.4639G>A [p.Val1547Ile]), and these results were reproducible on two different Sequencing platforms. All identified mutations induced hyperactivation of the mTOR pathway by disrupting the formation or function of the TSC1-TSC2 complex. Furthermore, in utero CRISPR-Cas9-mediated genome editing of Tsc1 or Tsc2 induced the development of spontaneous behavioral seizures, as well as cytomegalic neurons and cortical dyslamination. These results show that brain somatic mutations in TSC1 and TSC2 cause FCD and that in utero application of the CRISPR-Cas9 system is useful for generating neurodevelopmental disease models of somatic mutations in the brain.

Keywords

CRISPR-Cas9 genome editing; TSC1; TSC2; brain mosaicism; brain somatic mutation; focal cortical dysplasia; intractable epilepsy.

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