chr9-132921360-T-C

Position:

• chr9-132921360-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000368.5(TSC1):​c.737+3A>G variant causes a splice region, intron change. 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 Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TSC1 NM_000368.5 splice_region, intron
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:5 U:2 O:1
• Conservation: PhyloP100: 7.11

Genes affected

TSC1 (HGNC:12362): (TSC complex subunit 1) This gene is a tumor suppressor gene that encodes the growth inhibitory protein hamartin. The encoded protein interacts with and stabilizes the GTPase activating protein tuberin. This hamartin-tuberin complex negatively regulates mammalian target of rapamycin complex 1 (mTORC1) signaling which is a major regulator of anabolic cell growth. This protein also functions as a co-chaperone for Hsp90 that inhibits its ATPase activity. This protein functions as a facilitator of Hsp90-mediated folding of kinase and non-kinase clients, including TSC2 and thereby preventing their ubiquitination and proteasomal degradation. Mutations in this gene have been associated with tuberous sclerosis and lymphangioleiomyomatosis. [provided by RefSeq, May 2022]

TSC1 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC1	NM_000368.5	c.737+3A>G		splice_region_variant, intron_variant		ENST00000298552.9	NP_000359.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC1	ENST00000298552.9	c.737+3A>G		splice_region_variant, intron_variant		1	NM_000368.5	ENSP00000298552.3
TSC1	ENST00000490179.4	c.737+3A>G		splice_region_variant, intron_variant		3		ENSP00000495533.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:5 Uncertain:2 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Tuberous sclerosis 1 Pathogenic:3 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics, University of Leipzig Medical Center	Oct 01, 2024	Criteria applied: PS3_MOD,PS4_MOD,PM2_SUP,PP3 -
Uncertain significance, criteria provided, single submitter	clinical testing	Center for Human Genetics, Inc, Center for Human Genetics, Inc	Nov 01, 2016	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Mar 08, 2022	For these reasons, this variant has been classified as Pathogenic. 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. ClinVar contains an entry for this variant (Variation ID: 49093). This variant has been observed in individual(s) with clinical features of TSC1-related conditions (PMID: 29655203, 32313033; Invitae; the LOVD TSC1 database https//databases.lovd.nl/shared/individuals/00224510). In at least one individual the variant was observed to be de novo. It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change falls in intron 8 of the TSC1 gene. It does not directly change the encoded amino acid sequence of the TSC1 protein. It affects a nucleotide within the consensus splice site. -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	May 20, 2021	Observed in individuals with a personal or family history consistent with pathogenic variants in this gene referred for genetic testing at GeneDx and in published literature (Jones et al., 1997; Lindy et al., 2018); Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports a deleterious effect on splicing; This variant is associated with the following publications: (PMID: 29655203, 9328481, 32313033) -
Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Nov 28, 2022	- -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 22, 2016

The c.737+3A>G intronic variant results from an A to G substitution 3 nucleotides after coding exon 6 in the TSC1 gene. This nucleotide position is highly conserved in available vertebrate species. In one study, this alteration was observed in both normal controls and individuals with TSC (Jones AC et al. Hum. Mol. Genet., 1997 Nov;6:2155-61). Using two different splice site prediction tools, this alteration is predicted by BDGP to abolish the native splice donor site, but is predicted to weaken (but not abolish) the efficiency of the native splice donor site by ESEfinder; however, direct evidence is unavailable. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Tuberous sclerosis syndrome Other:1

not provided, no classification provided

curation

Tuberous sclerosis database (TSC1)

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.30
CADD	Benign	16
DANN	Benign	0.96
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.87		Position offset: 3

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

Publications

LitVar

Other links and lift over

dbSNP: rs118203439; hg19: chr9-135796747;