16-2056773-G-T

Variant names:

• chr16-2056773-G-T
• rs1244859914
• NM_000548.5:c.774+4G>T

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_000548.5(TSC2):​c.774+4G>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,454,992 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: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: TSC2 NM_000548.5 splice_region, intron
• Scores: Splicing: ADA: 0.0006765
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.199
• 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 -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.49).

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.774+4G>T		splice_region intron	N/A	NP_000539.2
	TSC2	NM_001406663.1		c.774+4G>T		splice_region intron	N/A	NP_001393592.1
	TSC2	NM_001114382.3		c.774+4G>T		splice_region intron	N/A	NP_001107854.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TSC2	ENST00000219476.9	TSL:5 MANE Select	c.774+4G>T		splice_region intron	N/A	ENSP00000219476.3
	TSC2	ENST00000350773.9	TSL:1	c.774+4G>T		splice_region intron	N/A	ENSP00000344383.4
	TSC2	ENST00000401874.7	TSL:1	c.774+4G>T		splice_region intron	N/A	ENSP00000384468.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1454992 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 724042

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86178

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 46750

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111936

Other (OTH) AF: 0.00 AC: 0 AN: 60340

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:1

Aug 22, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. 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 may create or strengthen a splice site. This variant has not been reported in the literature in individuals affected with TSC2-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change falls in intron 8 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.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.49
CADD	Benign	12
DANN	Benign	0.64
PhyloP100		0.20

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.00068
dbscSNV1_RF	Benign	0.066
SpliceAI score (max)		0.26		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.26		Position offset: -2

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

Other links and lift over

dbSNP: rs1244859914; hg19: chr16-2106774;