chr16-2062994-C-T

Position:

• chr16-2062994-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 6P and 4B. PM5 PP3_Strong BS2

The NM_000548.5(TSC2):​c.1384C>T​(p.Arg462Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000786 in 1,398,850 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R462P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000079 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 4.41

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-2062994-C-G is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.954
• BS2: High AC in GnomAdExome4 at 11 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TSC2	NM_000548.5	c.1384C>T	p.Arg462Cys	missense_variant	14/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.1384C>T	p.Arg462Cys	missense_variant	14/42	5	NM_000548.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000786 AC: 11 AN: 1398850 Hom.: 0 Cov.: 31 AF XY: 0.00000435 AC XY: 3 AN XY: 689958

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: 0.0000126

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000834

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2 Other:1

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

Oct 06, 2023

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 462 of the TSC2 protein (p.Arg462Cys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with tuberous sclerosis (PMID: 21520333, 22903760). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 65350). 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 TSC2 protein function. Experimental studies have shown that this missense change affects TSC2 function (PMID: 22903760). 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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 25, 2023

The p.R462C variant (also known as c.1384C>T), located in coding exon 13 of the TSC2 gene, results from a C to T substitution at nucleotide position 1384. The arginine at codon 462 is replaced by cysteine, an amino acid with highly dissimilar properties. This alteration has been reported in an individual meeting diagnostic criteria for tuberous sclerosis. This alteration demonstrated intermediate loss of the TSC1-TSC2 dependent inhibition of TORC1 and was associated with reduced TSC1 signals in functional studies performed (Hoogeveen-Westerveld M et al. Hum Mutat, 2013 Jan;34:167-75). 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. -

Tuberous sclerosis syndrome Other:1

not provided, no classification provided

curation

Tuberous sclerosis database (TSC2)

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.41	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	32
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.95	D;.;.;.;.;.;.;.;.;.;.;.;D;.;D
Eigen	Pathogenic	0.73
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.37	D
MetaRNN	Pathogenic	0.95	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.28	D
MutationAssessor	Uncertain	2.7	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-7.0	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
REVEL	Pathogenic	0.81
Sift	Uncertain	0.0010	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Uncertain	0.0040	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		0.99	D;.;.;.;D;D;.;.;D;D;.;.;.;.;.
Vest4		0.99
MutPred		0.79		Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);.;Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);.;Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);Loss of MoRF binding (P = 0.0071);.;
MVP		0.97
ClinPred		0.99	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.74
gMVP		0.88

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

Publications

LitVar

Other links and lift over

dbSNP: rs397515261; hg19: chr16-2112995; COSMIC: COSV54761376; COSMIC: COSV54761376;