chr16-2084477-C-T

Variant names:

• chr16-2084477-C-T
• rs45437193
• NM_000548.5:c.4255C>T

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.4255C>T​(p.Gln1419*) variant causes a stop gained change. 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 (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 34)
• Consequence: TSC2 NM_000548.5 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4 O:1
• 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 16-2084477-C-T is Pathogenic according to our data. Variant chr16-2084477-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 49821.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-2084477-C-T is described in Lovd as [Pathogenic]. Variant chr16-2084477-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.4255C>T	p.Gln1419*	stop_gained	Exon 34 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.4255C>T	p.Gln1419*	stop_gained	Exon 34 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis syndrome Pathogenic:1 Other:1

Jan 11, 2024

Cambridge Genomics Laboratory, East Genomic Laboratory Hub, NHS Genomic Medicine Service

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PVS1,PS4_Moderate -

-

Tuberous sclerosis database (TSC2)

Significance: not provided

Review Status: no classification provided

Collection Method: curation

- -

Tuberous sclerosis 2 Pathogenic:1

Sep 23, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Gln1419*) 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: 10205261). ClinVar contains an entry for this variant (Variation ID: 49821). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:1

Nov 18, 2019

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nonsense variant predicted to result in nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 25525159, 10205261, 10090883, 12111193, 15121797, 17304050, 28065512) -

Hereditary cancer-predisposing syndrome Pathogenic:1

Jan 18, 2017

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Q1419* variant (also known as c.4255C>T), located in coding exon 33 of the TSC2 gene, results from a C to T substitution at nucleotide position 4255. This changes the amino acid from a glutamine to a stop codon within coding exon 33. This mutation had been detected in multiple individuals meeting diagnostic criteria for tuberous sclerosis complex (TSC) (Jones AC et al. Am. J. Hum. Genet., 1999 May;64:1305-15; Cai Y et al. Urology, 2017 Jan; Roberts PS et al. J. Med. Genet., 2004 May;41:e69). This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	47
DANN	Uncertain	1.0
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Uncertain	0.96	D
Vest4		0.93
GERP RS		5.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.17		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: rs45437193; hg19: chr16-2134478; COSMIC: COSV99239307; COSMIC: COSV99239307;