16-2070493-G-T

Variant names:

• chr16-2070493-G-T
• rs397515063
• NM_000548.5:c.1754G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000548.5(TSC2):​c.1754G>T​(p.Arg585Leu) variant causes a missense 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R585C) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.89
• Publications: 0 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: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 19 benign, 39 uncertain in NM_000548.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.896

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000548.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TSC2	NM_000548.5	MANE Select	c.1754G>T	p.Arg585Leu	missense	Exon 17 of 42	NP_000539.2
	TSC2	NM_001406663.1		c.1754G>T	p.Arg585Leu	missense	Exon 17 of 42	NP_001393592.1
	TSC2	NM_001114382.3		c.1754G>T	p.Arg585Leu	missense	Exon 17 of 41	NP_001107854.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TSC2	ENST00000219476.9	TSL:5 MANE Select	c.1754G>T	p.Arg585Leu	missense	Exon 17 of 42	ENSP00000219476.3
	TSC2	ENST00000350773.9	TSL:1	c.1754G>T	p.Arg585Leu	missense	Exon 17 of 41	ENSP00000344383.4
	TSC2	ENST00000401874.7	TSL:1	c.1754G>T	p.Arg585Leu	missense	Exon 17 of 40	ENSP00000384468.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 34

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

Aug 16, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is not present in population databases (gnomAD no frequency). 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. 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. This variant has not been reported in the literature in individuals affected with TSC2-related conditions. This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 585 of the TSC2 protein (p.Arg585Leu).

Hereditary cancer-predisposing syndrome Uncertain:1

Oct 20, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.R585L variant (also known as c.1754G>T), located in coding exon 16 of the TSC2 gene, results from a G to T substitution at nucleotide position 1754. The arginine at codon 585 is replaced by leucine, an amino acid with dissimilar 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 v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.50
BayesDel_addAF	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.28
CADD	Benign	22
DANN	Benign	0.97
DEOGEN2	Pathogenic	0.82	D
Eigen	Benign	-0.038
Eigen_PC	Benign	-0.027
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D
M_CAP	Uncertain	0.15	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Uncertain	0.12	D
MutationAssessor	Benign	1.9	L
PhyloP100		7.9
PrimateAI	Uncertain	0.50	T
PROVEAN	Pathogenic	-4.8	D
REVEL	Pathogenic	0.72
Sift	Benign	0.15	T
Sift4G	Benign	0.27	T
Polyphen		0.73	P
Vest4		0.88
MutPred		0.71		Loss of methylation at R585 (P = 0.0202)
MVP		0.88
ClinPred		0.95	D
GERP RS		5.0
Varity_R		0.63
gMVP		0.71
Mutation Taster		=26/74	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: rs397515063; hg19: chr16-2120494;