chr16-2048754-G-C

Variant names:

• chr16-2048754-G-C
• rs45517091
• NM_000548.5:c.138+1G>C

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_000548.5(TSC2):​c.138+1G>C variant causes a splice donor, intron 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. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000040 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TSC2 NM_000548.5 splice_donor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 8.86
• 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: Pathogenic. The variant received 10 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 3.4, offset of 4, new splice context is: tgaGTgagc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage

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.138+1G>C		splice_donor intron	N/A	NP_000539.2
	TSC2	NM_001406663.1		c.138+1G>C		splice_donor intron	N/A	NP_001393592.1
	TSC2	NM_001114382.3		c.138+1G>C		splice_donor 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.138+1G>C		splice_donor intron	N/A	ENSP00000219476.3
	TSC2	ENST00000350773.9	TSL:1	c.138+1G>C		splice_donor intron	N/A	ENSP00000344383.4
	TSC2	ENST00000401874.7	TSL:1	c.138+1G>C		splice_donor intron	N/A	ENSP00000384468.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.0000398 AC: 58 AN: 1455726 Hom.: 0 Cov.: 32 AF XY: 0.0000386 AC XY: 28 AN XY: 724486

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

African (AFR) AF: 0.0000300 AC: 1 AN: 33344

American (AMR) AF: 0.00 AC: 0 AN: 44712

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26104

East Asian (EAS) AF: 0.00 AC: 0 AN: 39676

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86106

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53276

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5758

European-Non Finnish (NFE) AF: 0.0000488 AC: 54 AN: 1106544

Other (OTH) AF: 0.0000166 AC: 1 AN: 60206

⚠️ 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

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Uncertain	0.020
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		8.9
GERP RS		5.0
PromoterAI		-0.0080	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.90
SpliceAI score (max)		0.93		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.22		Position offset: 28
DS_DG_spliceai		0.51		Position offset: 3
DS_DL_spliceai		0.93		Position offset: -1

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

Other links and lift over

dbSNP: rs45517091; hg19: chr16-2098755;