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Imagerie cérébrale équipe Baulac

MOSAIC team

Genetic Mosaicism in Epilepsy and Neurodevelopmental Disorders

Stéphanie BAULAC
BAULAC Stéphanie

PhD, Team Leader, PI, INSERM

Team presentation

The team "Genetic Mosaicism in Epilepsy and Neurodevelopmental Disorders" focuses on focal epilepsies and malformations of cortical development.

The objective of the team is to elucidate the molecular and cellular mechanisms underlying focal epilepsies with malformations of cortical development, with a focus on somatic mutations.

The research is based on the concept that the human brain is a genetic mosaic resulting from somatic mutations acquired during neurodevelopment. Cortical malformations represent a preferred model for studying this mosaicism, allowing us to understand how mutations affecting a subset of neuronal cells can disrupt cortical architecture and generate epileptogenic foci. The team is using multidisciplinary approaches, from genetic and genomic studies on postoperative epileptic brain tissue, to in vitro functional tests using brain organoids, to in vivo approaches using mouse models.

The research program has three main objectives:

  1. To elucidate the genetic etiology of epileptogenic cortical malformations (in particular focal cortical dysplasia) by identifying somatic mutations in brain tissue;
  2. To understand the pathogenic and neurodevelopmental mechanisms underlying focal epilepsies by determining specific determinants of cell type in cortical organoids and mouse models;
  3. Investigate novel, precision targeted therapeutics to correct molecular abnormalities associated with cortical malformations.
     
Main publications

Main publications

2025

  • Baldassari S, Klingler E, Gomez Teijeiro L, Doladilhe M, Raoux C, Roig Puiggros S, Bizzotto S, Sami L, Ribierre T, Aronica E, Adle-Biassette H, Chipaux M, Jabaudon J and Baulac S. Single-cell genotyping and transcriptomic profiling in focal cortical dysplasia. Nat Neurosci. 2025. doi.org/10.1038/s41593-025-01936-z.

2024

  • Boßelmann, C.M., Leu, C., Brünger, T. Hoffmann L, Baldassari S, …, Baulac S, et al. Analysis of 1386 epileptogenic brain lesions reveals association with DYRK1A and EGFR. Nat Commun 15, 10429 (2024).
  • Ribierre T, Bacq A, Baldassari S, Maletic M, Roussel D, Donneger F, Doladilhe M, Le Roux I, Chassoux F, Devaux B, Adle-Biassette H, Ferrand-Sorbets S, Dorfmüller G, Chipaux M, Poncer JC and Baulac S. Targeting pathogenic cells reduces seizures in neurodevelopmental mTOR-related epilepsy. Nat Neurosci. 2024 Jun;27(6):1125-1136. doi: 10.1038/s41593-024-01634-2.

2023

  • Okoh J, Mays J, Bacq A, Chen C, Imambeyev K, Zhou H, Jafar-Nejad P, Noebels J, Baulac S and Costa-Mattioli M. Targeted suppression of mTORC2 reduces seizures across models of epilepsy. Nat Commun. 2023 Nov 14;14(1):7364. doi: 10.1038/s41467-023-42922-y.
  • Checri R, Chipaux M, Ferrand-Sorbets S, Raffo E, Bulteau C, Rosenberg SD, Doladilhe M, Dorfmüller G, Adle-Biassette H, Baldassari S, Baulac S. Detection of brain somatic mutations in focal cortical dysplasia during epilepsy presurgical workup. Brain Commun. 2023 Jun 1;5(3):fcad174. doi: 10.1093/braincomms/fcad174.
  • Chung C, Yang X, Bae T , Vong K, Mittal S , Conti V, Guerrini R, Devinsky O, Wilson A. Silva Jr 18, Helio R. Machado 7, Mathern G , Abyzov A, Baldassari S, Baulac S, Focal Cortical Dysplasia Neurogenetics Consortium &, Brain Somatic Mosaicism Network  and Gleeson J. Comprehensive multiomic profiling of somatic mutations in malformations of cortical development. Nat Genet. 2023 Feb;55(2):209-220. doi: 10.1038/s41588-022-01276-9

2021

  • Kim S*, Baldassari S*, Sim NS, Chipaux M, Dorfmüller G, Kim DS, Chang WS, Taly V, Lee JH and Baulac S. Detection of Brain Somatic Mutations in Cerebrospinal Fluid from Refractory Epilepsy Patients. Annals of Neurology 2021. Jun;89(6):1248-1252. doi: 10.1002/ana.26080.
  • Bonduelle T, Hartlieb T, Baldassari S, Sim NS, Kim SH, Kang HC, Kobow K, Coras R, Chipaux M, Dorfmüller G, Adle-Biassette H, Aronica E, Lee JH, Blumcke I and Baulac S. Frequent SLC35A2 brain mosaicism in mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). Acta Neuropathol Commun 2021 Jan 6;9(1):3. doi: 10.1186/s40478-020-01085-3 . 

2019

  • Baldassari S, Ribierre T, Marsan E, Adle-Biassette H, Ferrand-Sorbets S, Bulteau C, Dorison N, Fohlen M, Polivka M, Weckhuysen S, Dorfmüller G, Chipaux M, and Baulac S. Dissecting the genetic basis of focal cortical dysplasia: a large cohort study. Acta Neuropathol 2019 Dec;138(6):885-900. doi: 10.1007/s00401-019-02061-5.

2018

  • Ribierre T, Deleuze C, Bacq A, Baldassari S, Marsan E, Chipaux M, Muraca G, Roussel D, Navarro V, Leguern E, Miles R and Baulac S. Second-hit mosaic mutation in mTORC1 repressor DEPDC5 causes focal cortical dysplasia-associated epilepsy. Journal of Clinical Investigation 2018. Jun 1;128(6):2452-2458. doi: 10.1172/JCI99384.

Team members

Stéphanie BAULAC
BAULAC Stéphanie

PhD, Team Leader, PI, INSERM

Portrait Sara BALDASSARI
BALDASSARI Sara

PhD, PI

Eric LEGUERN
LEGUERN Éric

MD, PhD, Pr (PU-PH), PI

NAVA Caroline

MCU, PI, Sorbonne Université, AP-HP

News from the team

Analyse MERSCOPE
New treatment pathways for brain malformation-linked focal epilepsy?
A study by Stéphanie Baulac’s team has revealed somatic mutations in different cell types in patients with type 2 focal cortical dysplasia. This disease causes drug-resistant epileptic seizures, for which the main treatment option is currently...
05.12.2025 Research, science & health
erc
Three researchers from Paris Brain Institute awarded in 2023 an ERC STARTING GRANT
The European Research Council (ERC) has just published the list of recipients of “Starting grants” funding for 2023. The three candidates from Paris Brain Institute who applied to this highly competitive call for proposals have been awarded this...
09.05.2023 Institutional
image
Cardiac investigations in genetic epilepsy
A rare and tragic consequence of epilepsy is Sudden Unexpected Death in Epilepsy (SUDEP), which occurs after a seizure. The mechanisms involved, whether respiratory, cardiac or cerebral, are not yet fully understood. However, this risk is very low...
11.24.2021 Research, science & health
Logo L’Oréal-UNESCO
the L'Oréal-UNESCO Foundation rewards Maha DAHAWI, doctoral student at the Paris Brain Institute
The 2020 “Young Talents for Women and Science in Sub-Saharan Africa” prize from the L'Oréal-UNESCO Foundation rewards Maha DAHAWI, doctoral student at the Paris Brain Institute for her research carried out as a collaboration between France (Paris...
12.11.2020 Events
Stéphanie Baulac
Stéphanie Baulac receives the international epileptology award from the Michael foundation
Stéphanie Baulac, head of the “Genetics and physiopathology of epilepsy” at Institut du Cerveau - ICM, receives the international “Michael Prize” award for her research in the field of epilepsy.
04.17.2019 Institutional
Journée mondiale de l’épilepsie
National epilepsy day: research at the ICM
On the occasion of National Epilepsy Day, Vincent Navarro, neurologist and Institut du Cerveau - ICM researcher, and Stéphanie Baulac, co-leader of the team “Genetics and physiology of hereditary epilepsy,” and the start-up Bioserenity led a...
11.27.2015 Research, science & health