Brain somatic mutations are increasingly recognized as a major cause of focal epilepsies. These include mTOR pathway mutations underlying cortical malformations such as focal cortical dysplasia and hemimegalencephaly, and SLC35A2 mutations in MOGHE, and activating variants in the SHH pathway in hypothalamic hamartomas.

This study aims to identify brain somatic mutations using paired blood-brain samples and trace DNA from stereo-EEG electrodes, and to perform functional validation of candidate variants in children with drug-resistant focal epilepsy.

Inclusion Criteria:

• Children with focal drug-resistant epilepsy including Focal Cortical Dysplasia, Hemimegalencephaly, Tuberous Sclerosis, Mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE), Hypothalamic Hamartomas, Sturge-Weber syndrome, Rasmussen encephalitis, gliomas
• Their parents who have signed informed consent 1) for their child's participation (for parents) and 2) for themselves
• Social security coverage or foreign regime recognized in France

Exclusion Criteria:

• refusal to participate in the study
• contraindication to anaesthesia, to MRI or to surgery
• no medical insurance coverage

Children with focal drug-resistant epilepsy undergoing epilepsy surgery and their parents