1-11130747-C-T
Variant summary
Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PM1PM2PP3_ModeratePP5_Very_Strong
The NM_004958.4(MTOR):c.5395G>A(p.Glu1799Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).
Frequency
Consequence
NM_004958.4 missense
Scores
Clinical Significance
Conservation
Publications
- macrocephaly-intellectual disability-neurodevelopmental disorder-small thorax syndromeInheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Illumina, Orphanet, Labcorp Genetics (formerly Invitae), G2P
- overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genesInheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
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ACMG classification
Our verdict: Pathogenic. The variant received 14 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes Cov.: 32
GnomAD2 exomes AF: 0.00 AC: 0AN: 191474 AF XY: 0.00
GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0AN: 1428360Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0AN XY: 707194
GnomAD4 genome Cov.: 32
ClinVar
Submissions by phenotype
Macrocephaly-intellectual disability-neurodevelopmental disorder-small thorax syndrome Pathogenic:8Other:1
The MTOR c.5395G>A (p.Glu1799Lys) variant is a missense variant that has been described in a heterozygous state in at least 12 individuals from seven unrelated families with features of Smith-Kingsmore syndrome (Baynam et al. 2015; Mroske et al. 2015; Mirzaa et al. 2016; Moosa et al. 2017; Gordo et al. 2018; Dobyns and Mirzaa 2019). An additional feature of multiple intestinal polyps was reported in one individual. In multiple cases, the variant was shown to occur de novo. In at least three families, the variant was found in multiple affected children despite not being detected in the parent's blood, suggesting gonadal mosaicism. The p.Glu1799Lys variant is not reported in the Genome Aggregation Database in a region of good sequence coverage, so the variant is presumed to be rare. Glu1799 is located in the FAT domain, which serves to regulate MTOR activity, and experiments in patient cells, human cell lines, and cultured rodent neurons have confirmed a gain-of-function effect of the p.Glu1799Lys variant (Grabiner et al. 2014; Baynam et al. 2015; Mirzaa et al. 2016). Based on the collective evidence, the p.Glu1799Lys variant is classified as pathogenic for Smith-Kingsmore syndrome. -
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This variant was identified as de novo. -
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Variant summary: MTOR c.5395G>A (p.Glu1799Lys) results in a conservative amino acid change in the encoded protein sequence. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change. The frequency data for this variant in gnomAD is considered unreliable, as metrics indicate poor data quality at this position. c.5395G>A has been observed in multiple individuals affected with Smith-Kingsmore Syndrome and majority of them are de novo for this variant (Mroske_2015, Mirzaa_2016, Tatton-Brown_2017). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function and shows that this variant results in constitutive activation of MTOR protein (Mirzaa_2016). The following publications have been ascertained in the context of this evaluation (PMID: 27159400, 26542245, 28475857). ClinVar contains an entry for this variant (Variation ID: 217823). Based on the evidence outlined above, the variant was classified as pathogenic. -
Variant classified as Pathogenic and reported on 03-22-2021 by Illumina Clinical Services Laboratory. GenomeConnect assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. GenomeConnect staff make no attempt to reinterpret the clinical significance of the variant. -
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The variant is not observed in the gnomAD v2.1.1 dataset. Predicted Consequence/Location: The variant is located in a mutational hot spot and/or well-established functional domain in which established pathogenic variants have been reported (PMID: 23322780, 27482884, 21210909). Missense changes are a common disease-causing mechanism. In silico tool predictions suggest damaging effect of the variant on gene or gene product [REVEL: 0.64 (>=0.6, sensitivity 0.68 and specificity 0.92)]. Same nucleotide change resulting in same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000217823 /PMID: 25851998 /3billion dataset). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
not provided Pathogenic:4
PS4, PS3, PM6 -
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Functional studies indicate that E1799K results in an increase in mTOR pathway activity, suggesting a gain-of-function mechanism of disease (Baynam, et al., 2015); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 27739187, 27159400, 25851998, 26542245, 27513193, 27753196, 28892148, 28475857, 32581362, 33077954, 23636326, 24631838, 31441589, 31064327, 30764584, 30050716, 29296277, 27860216, 28007777, 24625776, 26432419) -
This sequence change replaces glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 1799 of the MTOR protein (p.Glu1799Lys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Smith–Kingsmore syndrome or MTOR-related megalencephaly and intellectual disability (PMID: 25851998, 26542245, 27159400, 27513193, 27753196, 28475857). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 217823). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MTOR protein function with a negative predictive value of 95%. Experimental studies have shown that this missense change affects MTOR function (PMID: 24631838, 25851998). For these reasons, this variant has been classified as Pathogenic. -
Intellectual disability Pathogenic:2
de novo variant, absent from gnomAD. Smith-Kingsmore syndrome -
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Inborn genetic diseases Pathogenic:1
The c.5395G>A (p.E1799K) alteration is located in exon 39 (coding exon 38) of the MTOR gene. This alteration results from a G to A substitution at nucleotide position 5395, causing the glutamic acid (E) at amino acid position 1799 to be replaced by a lysine (K). The MTOR c.5395G>A alteration was flagged as a low confidence call in the Genome Aggregation Database (gnomAD). This variant has been reported in multiple individuals with features consistent with Smith-Kingsmore syndrome; in at least one individual, it was determined to be de novo or the result of germline mosaicism (Baynam, 2015; Mroske, 2015; Moosa, 2017; Mirzaa, 2016; Poole, 2021; Ambry internal data). This amino acid position is highly conserved in available vertebrate species. The p.E1799 amino acid is located in the FAT domain of the MTOR protein, which binds to the kinase domain of the enzyme to negatively regulate MTOR activity (Yang, 2013). Structural modeling of the p.E1799K alteration suggests that this substitution destabilizes the FAT-kinase environment, leading to MTOR hyperactivation (Mroske, 2015). Functional analysis demonstrated that the p.E1799K alteration, which was originally identified in somatic tumor samples, results in activation of MTOR. Expression of MTOR with the p.E1799K alteration in HEK293 cells results in increased MTOR kinase activity towards AKT and 4E-Binding Protein 1, suggesting a gain-of-function effect (Grabiner, 2014). This alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, this alteration is classified as pathogenic. -
Rare genetic intellectual disability Pathogenic:1
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Intellectual disability, severe Pathogenic:1
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Isolated focal cortical dysplasia type II Pathogenic:1
This variant was determined to be pathogenic according to ACMG Guidelines, 2015 [PMID:25741868]. -
CEBALID syndrome Pathogenic:1
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Isolated focal cortical dysplasia type II;C4225259:Macrocephaly-intellectual disability-neurodevelopmental disorder-small thorax syndrome Pathogenic:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at