16-2075870-C-G

Position:

• chr16-2075870-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_000548.5(TSC2):​c.2617C>G​(p.Leu873Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,228 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. L873L) has been classified as Benign.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 3.22

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.779

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC2	NM_000548.5	c.2617C>G	p.Leu873Val	missense_variant	23/42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.2617C>G	p.Leu873Val	missense_variant	23/42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152228 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.0000941

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 33

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152228 Hom.: 0 Cov.: 33 AF XY: 0.0000134 AC XY: 1 AN XY: 74372

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.0000941

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 20, 2020

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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant has been reported in individuals in the Leiden Open-source Variation Database (PMID: 21520333). This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with valine at codon 873 of the TSC2 protein (p.Leu873Val). The leucine residue is highly conserved and there is a small physicochemical difference between leucine and valine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 30, 2024

The p.L873V variant (also known as c.2617C>G), located in coding exon 22 of the TSC2 gene, results from a C to G substitution at nucleotide position 2617. The leucine at codon 873 is replaced by valine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.27
CADD	Benign	21
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.79	D;.;.;.;.;.;.;.;.;.;.;.;D;.;D
Eigen	Uncertain	0.27
Eigen_PC	Benign	0.22
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.92	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.22	D
MetaRNN	Pathogenic	0.78	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.43	D
MutationAssessor	Uncertain	2.0	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	-2.3	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Pathogenic	0.79
Sift	Benign	0.12	T;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Uncertain	0.0080	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		0.99	D;.;.;.;D;D;.;.;D;P;.;.;.;.;.
Vest4		0.79
MutPred		0.69		Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);.;Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);.;Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);Gain of sheet (P = 0.0477);.;
MVP		0.96
ClinPred		0.92	D
GERP RS		3.1
Varity_R		0.24
gMVP		0.63

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555508418; hg19: chr16-2125871;