9-132921968-C-G

Variant names:

• chr9-132921968-C-G
• rs952813051
• NM_000368.5:c.514G>C

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1 PM2

The NM_000368.5(TSC1):​c.514G>C​(p.Val172Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V172M) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TSC1 NM_000368.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 7.91
• Publications: 2 publications found

Genes affected

TSC1 (HGNC:12362): (TSC complex subunit 1) This gene is a tumor suppressor gene that encodes the growth inhibitory protein hamartin. The encoded protein interacts with and stabilizes the GTPase activating protein tuberin. This hamartin-tuberin complex negatively regulates mammalian target of rapamycin complex 1 (mTORC1) signaling which is a major regulator of anabolic cell growth. This protein also functions as a co-chaperone for Hsp90 that inhibits its ATPase activity. This protein functions as a facilitator of Hsp90-mediated folding of kinase and non-kinase clients, including TSC2 and thereby preventing their ubiquitination and proteasomal degradation. Mutations in this gene have been associated with tuberous sclerosis and lymphangioleiomyomatosis. [provided by RefSeq, May 2022]

TSC1 Gene-Disease associations (from GenCC):

• tuberous sclerosis

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• tuberous sclerosis 1

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

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

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 6 benign, 23 uncertain in NM_000368.5
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC1	NM_000368.5	c.514G>C	p.Val172Leu	missense_variant	Exon 7 of 23	ENST00000298552.9	NP_000359.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC1	ENST00000298552.9	c.514G>C	p.Val172Leu	missense_variant	Exon 7 of 23	1	NM_000368.5	ENSP00000298552.3
TSC1	ENST00000490179.4	c.514G>C	p.Val172Leu	missense_variant	Exon 8 of 24	3		ENSP00000495533.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Jul 13, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Isolated focal cortical dysplasia type II Uncertain:1

Jan 03, 2024

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Tuberous sclerosis 1 Uncertain:1

Feb 14, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 172 of the TSC1 protein (p.Val172Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TSC1-related conditions. ClinVar contains an entry for this variant (Variation ID: 567652). 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 TSC1 protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Jun 03, 2020

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.V172L variant (also known as c.514G>C), located in coding exon 5 of the TSC1 gene, results from a G to C substitution at nucleotide position 514. The valine at codon 172 is replaced by leucine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. 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	0.24
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Pathogenic	0.14
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.48	T;.;T;.;T;.;T;.;.;.;.;.;.;.;.;.;.;T;.;.
Eigen	Uncertain	0.59
Eigen_PC	Uncertain	0.66
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.91	.;D;D;D;.;.;.;D;D;.;D;.;.;D;D;D;D;D;D;D
M_CAP	Uncertain	0.11	D
MetaRNN	Uncertain	0.55	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.35	D
MutationAssessor	Uncertain	2.5	M;.;M;.;M;.;M;.;.;.;.;.;.;.;.;.;.;.;.;.
PhyloP100		7.9
PrimateAI	Uncertain	0.69	T
PROVEAN	Benign	-0.43	N;N;N;.;.;.;.;.;.;.;.;.;.;.;.;.;.;N;.;.
REVEL	Uncertain	0.51
Sift	Benign	0.38	T;T;T;.;.;.;.;.;.;.;.;.;.;.;.;.;.;T;.;.
Sift4G	Uncertain	0.031	D;D;D;.;.;.;.;.;.;.;.;.;.;.;.;.;.;T;.;.
Polyphen		0.58	P;.;P;.;P;.;P;.;.;.;.;D;D;D;.;.;.;D;.;.
Vest4		0.76
MutPred		0.30		Loss of sheet (P = 0.0104);.;Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);.;.;Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);Loss of sheet (P = 0.0104);.;Loss of sheet (P = 0.0104);.;Loss of sheet (P = 0.0104);
MVP		0.51
MPC		1.4
ClinPred		0.81	D
GERP RS		6.1
Varity_R		0.11
gMVP		0.38
Mutation Taster		=47/53	disease causing

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

Other links and lift over

dbSNP: rs952813051; hg19: chr9-135797355;