16-2048066-G-A

Variant names:

• chr16-2048066-G-A
• rs587778004
• NM_000548.5:c.-30+1G>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_000548.5(TSC2):​c.-30+1G>A variant causes a splice donor, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000784 in 1,275,592 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.8e-7 (0 hom.)
• Consequence: TSC2 NM_000548.5 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.62
• 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]

NTHL1 (HGNC:8028): (nth like DNA glycosylase 1) The protein encoded by this gene is a DNA N-glycosylase of the endonuclease III family. Like a similar protein in E. coli, the encoded protein has DNA glycosylase activity on DNA substrates containing oxidized pyrimidine residues and has apurinic/apyrimidinic lyase activity. [provided by RefSeq, Oct 2008]

NTHL1 Gene-Disease associations (from GenCC):

• familial adenomatous polyposis 3

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, Genomics England PanelApp, Ambry Genetics
• NTHL1-deficiency tumor predisposition syndrome

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• breast cancer

  Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics
• meningioma

  Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.014933628 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.-30+1G>A		splice_donor_variant, intron_variant	Intron 1 of 41	ENST00000219476.9	NP_000539.2
NTHL1	NM_002528.7	c.-243C>T		upstream_gene_variant		ENST00000651570.2	NP_002519.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.-30+1G>A		splice_donor_variant, intron_variant	Intron 1 of 41	5	NM_000548.5	ENSP00000219476.3
NTHL1	ENST00000651570.2	c.-243C>T		upstream_gene_variant			NM_002528.7	ENSP00000498421.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 7.84e-7 AC: 1 AN: 1275592 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 620434

African (AFR) AF: 0.00 AC: 0 AN: 25440

American (AMR) AF: 0.00 AC: 0 AN: 19214

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 18440

East Asian (EAS) AF: 0.0000313 AC: 1 AN: 31898

South Asian (SAS) AF: 0.00 AC: 0 AN: 61854

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 32012

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4258

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1029644

Other (OTH) AF: 0.00 AC: 0 AN: 52832

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

Apr 02, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant occurs in a non-coding region of the TSC2 gene. It does not 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. 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 disrupt the consensus splice site. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.62
CADD	Pathogenic	31
DANN	Benign	0.84
PhyloP100		1.6
PromoterAI		-0.55	Under-expression
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.81
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.96		Position offset: -1

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

Other links and lift over

dbSNP: rs587778004; hg19: chr16-2098067; COSMIC: COSV99526611; COSMIC: COSV99526611;