The cytoplasmic dynein heavy chain (DYNC1H1) gene has been increasingly associated with neurodegenerative disorders including axonal Charcot-Marie-Tooth disease (CMT2), intellectual disability and malformations of cortical development.
Inputs from genetic studies were provided through the identification of several mutated genes encoding either proteins associated with microtubules (DCX, LIS1, KIF2A, KIF5C, DYNC1H1) or tubulin subunits (TUBA1A, TUBB2B, TUBB5 and TUBG1), in malformations of cortical development (MCD).
Patients with mammalian target of rapamycin (mTOR)-dependent malformations of cortical development (MCDs) associated with seizures display hyperperfusion and increased vessel density of the dysmorphic cortical tissue.
The mechanistic target of rapamycin (mTOR) pathway has been implicated in a growing number of malformations of cortical development (MCD) associated with intractable epilepsy.
A broad spectrum of malformations of cortical development, such as focal cortical dysplasia (FCD) and tuberous sclerosis complex (TSC), have been linked to either germline or somatic mutations in mTOR pathway-related genes, commonly summarised under the umbrella term 'mTORopathies'.
We review the neuroimaging findings in brain abnormalities related to alterations in the mTOR pathway, following the emerging trend from morphology towards genetics in the classification of malformations of cortical development.
Mutations in DEPDC5 and NPRL3 subunits of GATOR1, a modulator of mechanistic target of rapamycin (mTOR), are linked to malformations of cortical development (MCD).
Over the last decade, there has been increasing evidence that hyperactivation of the mechanistic target of rapamycin (mTOR) pathway is a hallmark of malformations of cortical development such as focal cortical dysplasia (FCD) or hemimegalencephaly.
Recently, a double-blind phase III randomized clinical trial on patients with TSC related epilepsy, demonstrated that adjunctive treatment with mTOR inhibition is effective and safe in reducing focal drug resistant seizures.Expert commentary. mTOR signaling dysregulation represents a common pathogenic mechanism in a subset of malformations of cortical development, sharing histopathological and clinical features, including epilepsy, autism, and intellectual disability.
Altogether, this study describes a molecular mechanism by which brain somatic mutations in MTOR contribute to the pathogenesis of cortical dyslamination in FMCDs.
Over the past decade enhanced activation of the mammalian target of rapamycin (mTOR)-signaling cascade has been identified in focal malformations of cortical development (MCD) subtypes, which have been collectively referred to as "mTORopathies."
Postzygotic somatic mutations activating the phosphatidylinositol-4,5-bisphosphate-3-kinase (PI3K)-protein kinase B (AKT)-mammalian target of rapamycin (mTOR) pathway are found in a wide range of brain diseases, including FMCDs.
As DEPDC5 is a negative regulator of the mammalian target of rapamycin (mTOR) pathway, it is likely that some patients with DEPDC5 mutations may have malformations of cortical development akin to the two-hit hypothesis suggested in tuberous sclerosis.
Inputs from genetic studies were provided through the identification of several mutated genes encoding either proteins associated with microtubules (DCX, LIS1, KIF2A, KIF5C, DYNC1H1) or tubulin subunits (TUBA1A, TUBB2B, TUBB5 and TUBG1), in malformations of cortical development (MCD).
The phenotypic spectrum associated with TUBB2B mutations is wider than previously reported and includes diffuse, symmetric malformations of cortical development.