chr16-2084476-ACAGT-A

Position:

• chr16-2084476-ACAGT-A

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.4258_4261del​(p.Ser1420GlyfsTer55) variant causes a frameshift change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. Q1419Q) has been classified as Likely benign. 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:5 O:2
• Conservation: PhyloP100: 4.30

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 16-2084476-ACAGT-A is Pathogenic according to our data. Variant chr16-2084476-ACAGT-A is described in ClinVar as [Pathogenic]. Clinvar id is 50083.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-2084476-ACAGT-A is described in Lovd as [Pathogenic]. Variant chr16-2084476-ACAGT-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TSC2	NM_000548.5	c.4258_4261del	p.Ser1420GlyfsTer55	frameshift_variant	34/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.4258_4261del	p.Ser1420GlyfsTer55	frameshift_variant	34/42	5	NM_000548.5

Frequencies

GnomAD3 genomes Cov.: 33

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5 Other:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 2 Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	3billion	Feb 23, 2023	The variant is not observed in the gnomAD v2.1.1 dataset. This variant was predicted to result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant. The variant has been reported at least twice as pathogenic with clinical assertions and evidence for the classification (PMID: 10533067). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 25, 2023	This sequence change creates a premature translational stop signal (p.Ser1420Glyfs*55) 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). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with tuberous sclerosis complex (PMID: 10533067, 29740858, 31855466). ClinVar contains an entry for this variant (Variation ID: 50083). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Mendelics	May 28, 2019	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -

Tuberous sclerosis syndrome Other:2

not provided, no classification provided	curation	Tuberous sclerosis database (TSC2)	-	- -
not provided, no classification provided	curation	Tuberous sclerosis database (TSC2)	-	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Mar 15, 2023

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Identified in patients with a clinical diagnosis of tuberous sclerosis complex in a well-curated database (TSC2 LOVD); This variant is associated with the following publications: (PMID: 16114042, 10533067, 26252095, 29740858, 31855466) -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.15		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: rs137854132; hg19: chr16-2134477;