16-2071925-C-CT

Position:

• chr16-2071925-C-CT

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000548.5(TSC2):​c.2090dup​(p.Leu697PhefsTer6) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TSC2 NM_000548.5 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4 O:1
• Conservation: PhyloP100: -0.283

Genes affected

TSC2 (HGNC:12363): (TSC complex subunit 2) This gene is a tumor suppressor gene that encodes the growth inhibitory protein tuberin. Tuberin interacts with hamartin to form the TSC protein complex which functions in the control of cell growth. This TSC protein complex negatively regulates mammalian target of rapamycin complex 1 (mTORC1) signaling which is a major regulator of anabolic cell growth. Mutations in this gene have been associated with tuberous sclerosis and lymphangioleiomyomatosis. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 16-2071925-C-CT is Pathogenic according to our data. Variant chr16-2071925-C-CT is described in ClinVar as [Pathogenic]. Clinvar id is 49650.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC2	NM_000548.5	c.2090dup	p.Leu697PhefsTer6	frameshift_variant	19/42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.2090dup	p.Leu697PhefsTer6	frameshift_variant	19/42	5	NM_000548.5	ENSP00000219476

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 2 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 01, 2022	This variant is not present in population databases (gnomAD no frequency). For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 49650). This premature translational stop signal has been observed in individual(s) with tuberous sclerosis complex (PMID: 16114042). This sequence change creates a premature translational stop signal (p.Leu697Phefs*6) in the TSC2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TSC2 are known to be pathogenic (PMID: 10205261, 17304050). -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Jun 03, 2020	The variant results in a shift of the reading frame, and is therefore predicted to result in the loss of a functional protein. Found in at least one patient with expected phenotype for this gene, and not found in general population data. -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jun 20, 2017	The c.2090dupT pathogenic variant in the TSC2 gene has been reported previously in an individual with a clinical diagnosis of TSC (Rendtorff et al., 2005). The duplication causes a frameshift starting with codon Leucine 697, changes this amino acid to a Phenylalanine residue and creates a premature Stop codon at position 6 of the new reading frame, denoted p.Leu697PhefsX6. This pathogenic variant is predicted to cause loss of normal protein function either through protein truncation or nonsense-mediated mRNA decay. Furthermore, the c.2090dupT variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). Therefore, the presence of c.2090dupT is consistent with a diagnosis of TSC in this individual. -

Tuberous sclerosis syndrome Other:1

not provided, no classification provided

curation

Tuberous sclerosis database (TSC2)

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Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs137854189; hg19: chr16-2121926;