chr16-2085322-G-A

Variant names:

• chr16-2085322-G-A
• rs137854880
• NM_000548.5:c.4662G>A

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM2 PP3 PP5_Very_Strong

The NM_000548.5(TSC2):​c.4662G>A​(p.Gln1554Gln) variant causes a splice region, synonymous change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 34)
• Consequence: TSC2 NM_000548.5 splice_region, synonymous
• Scores: Splicing: ADA: 0.9991
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 9.66
• Publications: 3 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: Pathogenic. The variant received 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 16-2085322-G-A is Pathogenic according to our data. Variant chr16-2085322-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 49485.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

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.4662G>A	p.Gln1554Gln	splice_region synonymous	Exon 36 of 42	NP_000539.2
	TSC2	NM_001406663.1		c.4659G>A	p.Gln1553Gln	splice_region synonymous	Exon 36 of 42	NP_001393592.1
	TSC2	NM_001114382.3		c.4593G>A	p.Gln1531Gln	splice_region synonymous	Exon 35 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.4662G>A	p.Gln1554Gln	splice_region synonymous	Exon 36 of 42	ENSP00000219476.3
	TSC2	ENST00000350773.9	TSL:1	c.4593G>A	p.Gln1531Gln	splice_region synonymous	Exon 35 of 41	ENSP00000344383.4
	TSC2	ENST00000401874.7	TSL:1	c.4461G>A	p.Gln1487Gln	splice_region synonymous	Exon 34 of 40	ENSP00000384468.2

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis syndrome Pathogenic:1 Other:1

Tuberous sclerosis database (TSC2)

Significance: not provided

Review Status: no classification provided

Collection Method: curation

Sep 23, 2024

All of Us Research Program, National Institutes of Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.4662G>A (p.Gln1554=) variant in the TSC2 gene is a synonymous variant located at the last nucleotide of exon 36, which is part of the consensus splice site for this exon. This nucleotide substitution is predicted to affect normal splicing (SpliceAI donor loss score: 0.65 at the canonical donor splice site, and donor gain score: 0.5 at 23 nucleotides downstream). To our knowledge, functional studies demonstrating the impact of this variant on RNA splicing have not been reported for this variant. This variant has been reported in at least four individuals affected with tuberous sclerosis, with de novo occurrence reported in three individuals (ClinVar ID: 49485 (SCV001396837.5, SCV000066540.3); LOVD). This variant is absent in the general population according to gnomAD. Therefore, c.4662G>A (p.Gln1554=) variant in TSC2 gene is classified as pathogenic.

Tuberous sclerosis 2 Pathogenic:1

Jul 18, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects codon 1554 of the TSC2 mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the TSC2 protein. This variant also falls at the last nucleotide of exon 36 of the TSC2 coding sequence, which is part of the consensus splice site for this exon. This variant is not present in population databases (ExAC no frequency). This variant has been observed to be de novo in an individual affected with tuberous sclerosis (Invitae). ClinVar contains an entry for this variant (Variation ID: 49485). For these reasons, this variant has been classified as Pathogenic. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.45
CADD	Uncertain	23
DANN	Benign	0.80
PhyloP100		9.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8
Mutation Taster		=4/96	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.65		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.50		Position offset: 23
DS_DL_spliceai		0.65		Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs137854880; hg19: chr16-2135323;