Dataset Information

Is Focal Cortical Dysplasia/Epilepsy Caused by Somatic MTOR Mutations Always a Unilateral Disorder?

ABSTRACT:

Objective

To alert about the wide margin of unpredictability that distribution of somatic MTOR mosaicism may have in the brain and the risk for independent epileptogenesis arising from the seemingly healthy contralateral hemisphere after complete removal of epileptogenic focal cortical dysplasia (FCD).

Methods

Clinical, EEG, MRI, histopathology, and molecular genetics in 2 patients (1 and 2) treated with focal resections and subsequent complete hemispherectomy for epileptogenic FCD due to somatic MTOR mutations. Autoptic brain study of bilateral asymmetric hemispheric dysplasia and identification of alternative allele fraction (AAF) rates for AKT1 (patient 3).

Results

The strongly hyperactivating p.Ser2215Phe (patient 1) and p.Leu1460Pro (patient 2) MTOR mutations were at low-level AAF in the dysplastic tissue. After repeated resections and eventual complete hemispherectomy, both patients manifested intractable seizures arising from the contralateral, seemingly healthy hemisphere. In patient 3, the p.Glu17Lys AKT1 mutation exhibited random distribution and AAF rates in different tissues with double levels in the more severely dysplastic cerebral hemisphere.

Conclusions

Our understanding of the distribution of somatic mutations in the brain in relation to the type of malformation and its hypothesized time of origin may be faulty. Large studies may reveal that the risk of a first surgery being disappointing might be related more to the specific somatic mammalian target of rapamycin mutation identified than to completeness of resection and that the advantages of repeated resections after a first unsuccessful operation should be weighed against the risk of the contralateral hemisphere becoming in turn epileptogenic.

SUBMITTER: Guerrini R

PROVIDER: S-EPMC7735020 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Is Focal Cortical Dysplasia/Epilepsy Caused by Somatic <i>MTOR</i> Mutations Always a Unilateral Disorder?

Guerrini Renzo R Cavallin Mara M Pippucci Tommaso T Rosati Anna A Bisulli Francesca F Dimartino Paola P Barba Carmen C Garbelli Rita R Buccoliero Anna Maria AM Tassi Laura L Conti Valerio V

Neurology. Genetics 20201208 1

<h4>Objective</h4>To alert about the wide margin of unpredictability that distribution of somatic <i>MTOR</i> mosaicism may have in the brain and the risk for independent epileptogenesis arising from the seemingly healthy contralateral hemisphere after complete removal of epileptogenic focal cortical dysplasia (FCD).<h4>Methods</h4>Clinical, EEG, MRI, histopathology, and molecular genetics in 2 patients (1 and 2) treated with focal resections and subsequent complete hemispherectomy for epileptog ...[more]

PMID: 33542949

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