NM_000548.5:c.1771G>A

Variant names:

• chr16-2070510-G-A
• rs984275273
• NM_000548.5:c.1771G>A

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 4P and 3B. PM1 PM2 BP4_Moderate BP6

The NM_000548.5(TSC2):​c.1771G>A​(p.Val591Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,056 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict 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. V591G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:1
• Conservation: PhyloP100: 2.19
• Publications: 4 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: Uncertain_significance. The variant received 1 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 15 benign, 33 uncertain in NM_000548.5
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.17218831).
• BP6: Variant 16-2070510-G-A is Benign according to our data. Variant chr16-2070510-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 467894.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.1771G>A	p.Val591Ile	missense_variant	Exon 17 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.1771G>A	p.Val591Ile	missense_variant	Exon 17 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000399 AC: 1 AN: 250794 AF XY: 0.00000736

Gnomad AFR exome AF: 0.0000618

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461056 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 726842

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

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

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52610

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111996

Other (OTH) AF: 0.00 AC: 0 AN: 60388

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Tuberous sclerosis syndrome Uncertain:1

Jun 26, 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 valine with isoleucine at codon 591 of the TSC2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with tuberous sclerosis complex in the literature. This variant has been identified in 1/250794 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

May 10, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.V591I variant (also known as c.1771G>A), located in coding exon 16 of the TSC2 gene, results from a G to A substitution at nucleotide position 1771. The valine at codon 591 is replaced by isoleucine, an amino acid with highly similar properties. This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Tuberous sclerosis 2 Benign:1

Aug 16, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.081
BayesDel_addAF	Benign	-0.10	T
BayesDel_noAF	Benign	-0.21
CADD	Benign	7.0
DANN	Benign	0.15
DEOGEN2	Uncertain	0.42	T;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	-0.82
Eigen_PC	Benign	-0.65
FATHMM_MKL	Benign	0.63	D
LIST_S2	Benign	0.83	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
M_CAP	Benign	0.022	T
MetaRNN	Benign	0.17	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.89	T
MutationAssessor	Benign	0.12	N;.;.;.;N;N;.;.;.;N;.;N;.;.;.
PhyloP100		2.2
PrimateAI	Benign	0.34	T
PROVEAN	Benign	0.15	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Uncertain	0.38
Sift	Benign	0.68	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Benign	1.0	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Polyphen		0.0	B;.;.;.;B;B;.;.;B;B;.;.;.;.;.
Vest4		0.31
MutPred		0.58		Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);.;Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);.;Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);Gain of catalytic residue at V591 (P = 0.1801);.;
MVP		0.81
ClinPred		0.018	T
GERP RS		3.4
Varity_R		0.018
gMVP		0.21
Mutation Taster		=99/1	polymorphism

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: rs984275273; hg19: chr16-2120511;