mTOR Pathway Somatic Pathogenic Variants in Focal Malformations of Cortical Development: Novel Variants, Topographic Mapping, and Clinical Outcomes.
Journal
Neurology. Genetics
ISSN: 2376-7839
Titre abrégé: Neurol Genet
Pays: United States
ID NLM: 101671068
Informations de publication
Date de publication:
Dec 2023
Dec 2023
Historique:
received:
21
04
2023
accepted:
06
09
2023
medline:
30
10
2023
pubmed:
30
10
2023
entrez:
30
10
2023
Statut:
epublish
Résumé
Somatic and germline pathogenic variants in genes of the mammalian target of rapamycin (mTOR) signaling pathway are a common mechanism underlying a subset of focal malformations of cortical development (FMCDs) referred to as mTORopathies, which include focal cortical dysplasia (FCD) type II, subtypes of polymicrogyria, and hemimegalencephaly. Our objective is to screen resected FMCD specimens with mTORopathy features on histology for causal somatic variants in mTOR pathway genes, describe novel pathogenic variants, and examine the variant distribution in relation to neuroimaging, histopathologic classification, and clinical outcomes. We performed ultra-deep sequencing using a custom HaloPlex We identified causal mTOR pathway gene variants in 66.7% (14/21) of patients, of which 13 were somatic with AAF ranging between 0.6% and 12.0%. Moreover, the AAF did not predict balloon cell presence. Favorable seizure outcomes were associated with genetically clear resection borders. Individuals in whom a causal somatic variant was undetected had excellent postsurgical outcomes. In addition, we demonstrate pathogenicity of the novel c.4373_4375dupATG and candidate c.7499T>A The AAF of somatic pathogenic variants correlated with the topographic distribution, histopathology, and postsurgical outcomes. Moreover, cortical regions with absent histologic FCD features had negligible or undetectable pathogenic variant loads. By contrast, specimens with frank histologic abnormalities had detectable pathogenic variant loads, which raises important questions as to whether there is a tolerable variant threshold and whether surgical margins should be clean, as performed in tumor resections. In addition, we describe 2 novel pathogenic variants, expanding the mTORopathy genetic spectrum. Although most pathogenic somatic variants are located at mutation hotspots, screening the full-coding gene sequence remains necessary in a subset of patients.
Sections du résumé
Background and Objectives
UNASSIGNED
Somatic and germline pathogenic variants in genes of the mammalian target of rapamycin (mTOR) signaling pathway are a common mechanism underlying a subset of focal malformations of cortical development (FMCDs) referred to as mTORopathies, which include focal cortical dysplasia (FCD) type II, subtypes of polymicrogyria, and hemimegalencephaly. Our objective is to screen resected FMCD specimens with mTORopathy features on histology for causal somatic variants in mTOR pathway genes, describe novel pathogenic variants, and examine the variant distribution in relation to neuroimaging, histopathologic classification, and clinical outcomes.
Methods
UNASSIGNED
We performed ultra-deep sequencing using a custom HaloPlex
Results
UNASSIGNED
We identified causal mTOR pathway gene variants in 66.7% (14/21) of patients, of which 13 were somatic with AAF ranging between 0.6% and 12.0%. Moreover, the AAF did not predict balloon cell presence. Favorable seizure outcomes were associated with genetically clear resection borders. Individuals in whom a causal somatic variant was undetected had excellent postsurgical outcomes. In addition, we demonstrate pathogenicity of the novel c.4373_4375dupATG and candidate c.7499T>A
Discussion
UNASSIGNED
The AAF of somatic pathogenic variants correlated with the topographic distribution, histopathology, and postsurgical outcomes. Moreover, cortical regions with absent histologic FCD features had negligible or undetectable pathogenic variant loads. By contrast, specimens with frank histologic abnormalities had detectable pathogenic variant loads, which raises important questions as to whether there is a tolerable variant threshold and whether surgical margins should be clean, as performed in tumor resections. In addition, we describe 2 novel pathogenic variants, expanding the mTORopathy genetic spectrum. Although most pathogenic somatic variants are located at mutation hotspots, screening the full-coding gene sequence remains necessary in a subset of patients.
Identifiants
pubmed: 37900581
doi: 10.1212/NXG.0000000000200103
pii: NXG-2023-000101
pmc: PMC10602370
doi:
Types de publication
Journal Article
Langues
eng
Pagination
e200103Informations de copyright
Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.
Déclaration de conflit d'intérêts
The authors report no relevant disclosures. Go to Neurology.org/NG for full disclosures.
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