mTOR pathway somatic variants and the molecular pathogenesis of hemimegalencephaly

Epilepsia Open
Camila A B GarciaHélio R Machado

Abstract

Recently, defects in the protein kinase mTOR (mammalian target of rapamycin) and its associated pathway have been correlated with hemimegalencephaly (HME). mTOR acts as a central regulator of important physiological cellular functions such as growth and proliferation, metabolism, autophagy, death, and survival. This study was aimed at identifying specific variants in mTOR signaling pathway genes in patients diagnosed with HME. Using amplicon and whole exome sequencing (WES) of resected brain and paired blood samples from five HME patients, we were able to identify pathogenic mosaic variants in the mTOR pathway genes MTOR, PIK3CA, and DEPDC5. These results strengthen the hypothesis that somatic variants in PI3K-Akt-mTOR pathway genes contribute to HME. We also describe one patient presenting with a pathogenic variant on DEPDC5 gene, which reinforces the role of DEPDC5 on cortical structural changes due to mTORC1 hyperactivation. These findings also provide insights into when in brain development these variants occurred. An early developmental variant is expected to affect a larger number of cells and to result in a larger malformation, whereas the same variant occurring later in development would cause a minor malformation. In t...Continue Reading

References

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Methods Mentioned

BETA
biopsy
amplicon sequencing
PCR
exome sequencing

Software Mentioned

tools
Ensembl Variant Effect Predictor VEP
QuantaSoft
SnpEff
MutationTaster
bwa
umi
muTect2
mem
IndelRealigner

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