9-132925592-G-T

Variant names:

• chr9-132925592-G-T
• rs1554820263
• NM_000368.5:c.358C>A

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000368.5(TSC1):​c.358C>A​(p.Leu120Ile) variant causes a missense 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. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L120F) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TSC1 NM_000368.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.76
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• tuberous sclerosis

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• tuberous sclerosis 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, PanelApp Australia, Genomics England PanelApp, G2P, Labcorp Genetics (formerly Invitae)
• lung lymphangioleiomyomatosis

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• tuberous sclerosis complex

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 10 benign, 23 uncertain in NM_000368.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.818

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC1	NM_000368.5	c.358C>A	p.Leu120Ile	missense_variant	Exon 5 of 23	ENST00000298552.9	NP_000359.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC1	ENST00000298552.9	c.358C>A	p.Leu120Ile	missense_variant	Exon 5 of 23	1	NM_000368.5	ENSP00000298552.3
TSC1	ENST00000490179.4	c.358C>A	p.Leu120Ile	missense_variant	Exon 6 of 24	3		ENSP00000495533.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 1 Uncertain:1

Sep 03, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces leucine with isoleucine at codon 120 of the TSC1 protein (p.Leu120Ile). The leucine residue is highly conserved and there is a small physicochemical difference between leucine and isoleucine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with TSC1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Mar 18, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.L120I variant (also known as c.358C>A), located in coding exon 3 of the TSC1 gene, results from a C to A substitution at nucleotide position 358. The leucine at codon 120 is replaced by isoleucine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. Based on the available evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.48
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.52	D;D;.;D;.;D;.;.;.;.;.;.;.;D;.;.
Eigen	Pathogenic	0.96
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	.;D;D;.;.;.;D;D;.;.;D;D;D;D;D;D
M_CAP	Uncertain	0.11	D
MetaRNN	Pathogenic	0.82	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.41	D
MutationAssessor	Uncertain	2.5	M;M;.;M;.;M;.;.;.;.;.;.;.;.;.;.
PhyloP100		9.8
PrimateAI	Uncertain	0.79	T
PROVEAN	Benign	-1.4	N;N;.;.;.;.;.;.;.;.;.;.;.;N;.;.
REVEL	Uncertain	0.64
Sift	Uncertain	0.0090	D;D;.;.;.;.;.;.;.;.;.;.;.;T;.;.
Sift4G	Pathogenic	0.0	D;D;.;.;.;.;.;.;.;.;.;.;.;D;.;.
Polyphen		0.98	D;D;.;D;.;D;.;.;D;D;D;.;.;D;.;.
Vest4		0.88
MutPred		0.71		Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);Loss of catalytic residue at L120 (P = 0.0533);
MVP		0.51
MPC		1.4
ClinPred		0.97	D
GERP RS		5.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.40
gMVP		0.33
Mutation Taster		=51/49	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs1554820263; hg19: chr9-135800979;