16-2077722-C-T

Variant names:

• chr16-2077722-C-T
• rs763047420
• NM_000548.5:c.2962C>T

Variant summary

Our verdict is Likely benign. The variant received -6 ACMG points: 0P and 6B. BP4 BP6 BS2

The NM_000548.5(TSC2):​c.2962C>T​(p.Arg988Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000616 in 1,460,268 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R988H) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:3
• Conservation: PhyloP100: 4.95
• Publications: 7 publications found

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]

TSC2 Gene-Disease associations (from GenCC):

• tuberous sclerosis

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• tuberous sclerosis 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp, Ambry Genetics
• lymphangioleiomyomatosis

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• tuberous sclerosis complex

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -6 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.3823319).
• BP6: Variant 16-2077722-C-T is Benign according to our data. Variant chr16-2077722-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 467979.
• BS2: High AC in GnomAdExome4 at 9 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.2962C>T	p.Arg988Cys	missense_variant	Exon 26 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.2962C>T	p.Arg988Cys	missense_variant	Exon 26 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.0000160 AC: 4 AN: 250072 AF XY: 0.0000147

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000109

Gnomad FIN exome AF: 0.0000467

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1460268 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 726464

African (AFR) AF: 0.0000299 AC: 1 AN: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39698

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86242

European-Finnish (FIN) AF: 0.0000192 AC: 1 AN: 52040

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5614

European-Non Finnish (NFE) AF: 0.00000360 AC: 4 AN: 1111980

Other (OTH) AF: 0.00 AC: 0 AN: 60362

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Tuberous sclerosis 2 Benign:3

Nov 07, 2021

Genome-Nilou Lab

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 14, 2024

Myriad Genetics, Inc.

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely benign. This variant has been observed at a population frequency that is significantly greater than expected given the associated disease prevalence and penetrance. -

Tuberous sclerosis syndrome Uncertain:1

Jul 10, 2023

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces arginine with cysteine at codon 988 of the TSC2 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with TSC2-related disorders in the literature. This variant has been identified in 4/250072 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

not provided Uncertain:1

Jan 21, 2019

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect; Functional studies demonstrate no damaging effect (TSC2 LOVD); This variant is associated with the following publications: (PMID: 21520333, 26703369, 28492532) -

Hereditary cancer-predisposing syndrome Uncertain:1

Apr 05, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.R988C variant (also known as c.2962C>T), located in coding exon 25 of the TSC2 gene, results from a C to T substitution at nucleotide position 2962. The arginine at codon 988 is replaced by cysteine, an amino acid with highly dissimilar properties. This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.036	T
BayesDel_noAF	Uncertain	0.040
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.73	D;.;.;.
Eigen	Benign	0.0029
Eigen_PC	Benign	0.12
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.89	D;D;D;D
M_CAP	Uncertain	0.087	D
MetaRNN	Benign	0.38	T;T;T;T
MetaSVM	Uncertain	0.096	D
MutationAssessor	Benign	1.2	L;.;.;L
PhyloP100		4.9
PrimateAI	Uncertain	0.53	T
PROVEAN	Uncertain	-3.4	D;.;.;D
REVEL	Uncertain	0.57
Sift	Uncertain	0.022	D;.;.;D
Sift4G	Uncertain	0.0020	D;.;.;D
Polyphen		0.0090	B;.;.;B
Vest4		0.58
MutPred		0.42		Loss of MoRF binding (P = 0.0027);Loss of MoRF binding (P = 0.0027);Loss of MoRF binding (P = 0.0027);Loss of MoRF binding (P = 0.0027);
MVP		0.93
ClinPred		0.55	D
GERP RS		4.1
Varity_R		0.26
gMVP		0.57
Mutation Taster		=73/27	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs763047420; hg19: chr16-2127723;