16-2058784-G-T

Position:

• chr16-2058784-G-T

Variant summary

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

The NM_001406689.1(TSC2):​c.-546G>T variant causes a 5 prime UTR premature start codon gain change involving the alteration of a conserved nucleotide. 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TSC2 NM_001406689.1 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.51

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, 0.785

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC2	NM_000548.5	c.886G>T	p.Val296Leu	missense_variant	10/42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.886G>T	p.Val296Leu	missense_variant	10/42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1441318 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 714914

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

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

Apr 10, 2019

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: "Benign"; Align-GVGD: "Class C25"). This variant has not been reported in the literature in individuals with TSC2-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces valine with leucine at codon 296 of the TSC2 protein (p.Val296Leu). The valine residue is highly conserved and there is a small physicochemical difference between valine and leucine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 05, 2022

The p.V296L variant (also known as c.886G>T), located in coding exon 9 of the TSC2 gene, results from a G to T substitution at nucleotide position 886. The valine at codon 296 is replaced by leucine, 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. 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	Pathogenic	0.84
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.30
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.67	D;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Pathogenic	0.85
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.46	D
MetaRNN	Pathogenic	0.78	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.63	D
MutationAssessor	Benign	1.6	L;.;.;.;L;L;.;.;.;L;.;L;.;.;.
PrimateAI	Pathogenic	0.80	T
PROVEAN	Benign	-2.3	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Pathogenic	0.68
Sift	Benign	0.079	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Pathogenic	0.0	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		0.99	D;.;.;.;D;D;.;.;D;D;.;.;.;.;.
Vest4		0.82
MutPred		0.43		Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);.;Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);.;Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);Gain of helix (P = 0.0496);.;
MVP		0.92
ClinPred		0.94	D
GERP RS		5.1
Varity_R		0.51
gMVP		0.74

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs747237113; hg19: chr16-2108785;