chr16-2077595-T-G

Variant names:

• chr16-2077595-T-G
• rs553942147
• NM_000548.5:c.2838-3T>G

Variant summary

Our verdict is Likely benign. The variant received -6 ACMG points: 0P and 6B. BP4_Moderate BS2

The NM_000548.5(TSC2):​c.2838-3T>G variant causes a splice region, intron change. The variant allele was found at a frequency of 0.00000753 in 1,460,672 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000075 (0 hom.)
• Consequence: TSC2 NM_000548.5 splice_region, intron
• Scores: Splicing: ADA: 0.9935
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 5.12
• 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_benign. The variant received -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.39).
• BS2: High AC in GnomAdExome4 at 11 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.2838-3T>G		splice_region_variant, intron_variant	Intron 25 of 41	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.2838-3T>G		splice_region_variant, intron_variant	Intron 25 of 41	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000753 AC: 11 AN: 1460672 Hom.: 0 Cov.: 31 AF XY: 0.00000963 AC XY: 7 AN XY: 726638

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86248

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52328

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5726

European-Non Finnish (NFE) AF: 0.00000899 AC: 10 AN: 1111970

Other (OTH) AF: 0.0000166 AC: 1 AN: 60370

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:2

Nov 07, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 07, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change falls in intron 25 of the TSC2 gene. It does not directly change the encoded amino acid sequence of the TSC2 protein. It affects a nucleotide within the consensus splice site. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TSC2-related conditions. ClinVar contains an entry for this variant (Variation ID: 424000). Variants that disrupt 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 is not likely to affect RNA splicing. 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. -

not provided Uncertain:1

Mar 10, 2017

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A variant of uncertain significance has been identified in the TSC2 gene. The c.2838-3 T>G variant has not been published as a pathogenic variant, nor has it been reported as a benign variant to our knowledge. The c.2838-3 T>G variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). An in-silico splice prediction model predicts that c.2838-3 T>G may destroy the natural acceptor site of intron 25 and lead to abnormal gene splicing. However, in the absence of RNA/functional studies, the actual effect of this sequence change in this individual is unknown. Therefore, based on the currently available information, it is unclear whether this variant is a pathogenic variant or a rare benign variant. -

Hereditary cancer-predisposing syndrome Uncertain:1

Aug 19, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2838-3T>G intronic variant results from a T to G substitution 3 nucleotides upstream from coding exon 25 in the TSC2 gene. This nucleotide position is well conserved in available vertebrate species. In silico splice site analysis for this alteration is inconclusive. However, this alteration occurs at the splice acceptor site for an exon that is absent in biologically relevant transcripts (Ekong R et al. Hum. Mutat. 2016 Apr; 37:362-70). Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.39
CADD	Benign	20
DANN	Benign	0.89
PhyloP100		5.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.99
dbscSNV1_RF	Benign	0.70
SpliceAI score (max)		0.18		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: rs553942147; hg19: chr16-2127596;