9-132902720-G-A

Position:

• chr9-132902720-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The ENST00000298552.9(TSC1):​c.2276C>T​(p.Ala759Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign 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. A759T) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TSC1 ENST00000298552.9 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.84

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TSC1. . Gene score misZ 2.3217 (greater than the threshold 3.09). Trascript score misZ 3.6986 (greater than threshold 3.09). GenCC has associacion of gene with lung lymphangioleiomyomatosis, tuberous sclerosis 1, tuberous sclerosis, tuberous sclerosis complex, lymphangioleiomyomatosis.
• BP4: Computational evidence support a benign effect (MetaRNN=0.11270386).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC1	NM_000368.5	c.2276C>T	p.Ala759Val	missense_variant	18/23	ENST00000298552.9	NP_000359.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC1	ENST00000298552.9	c.2276C>T	p.Ala759Val	missense_variant	18/23	1	NM_000368.5	ENSP00000298552	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 1 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	St. Jude Molecular Pathology, St. Jude Children's Research Hospital	Dec 21, 2021	The TSC1 c.2276C>T (p.Ala759Val) missense change is absent form gnomAD v2.1.1 (PM2_supporting; https://gnomad.broadinstitute.org/). Five of seven in silico tools predict a benign effect of this variant on protein function (BP4), but to our knowledge these predictions have not been confirmed by functional assays. To our knowledge, this variant has not been reported in individuals with tuberous sclerosis complex. In summary, this variant meets criteria to be classified as of uncertain significance based on the ACMG/AMP criteria: PM2_supporting, BP4. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 24, 2023	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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt TSC1 protein function. ClinVar contains an entry for this variant (Variation ID: 466071). This variant has not been reported in the literature in individuals affected with TSC1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 759 of the TSC1 protein (p.Ala759Val). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.099
BayesDel_addAF	Benign	-0.059	T
BayesDel_noAF	Benign	-0.32
CADD	Benign	20
DANN	Uncertain	0.99
DEOGEN2	Benign	0.37	T;.;T;.;.;T;.;T;.;.;.
Eigen	Benign	-0.28
Eigen_PC	Benign	-0.069
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Uncertain	0.88	.;D;D;D;D;.;.;.;D;D;.
M_CAP	Benign	0.025	T
MetaRNN	Benign	0.11	T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.80	T
MutationAssessor	Benign	0.41	N;.;N;.;.;N;.;N;.;.;.
MutationTaster	Benign	1.0	D;N;N;N
PrimateAI	Benign	0.38	T
PROVEAN	Benign	-0.58	N;N;N;.;.;.;.;.;.;.;.
REVEL	Benign	0.29
Sift	Benign	0.30	T;T;T;.;.;.;.;.;.;.;.
Sift4G	Benign	0.29	T;T;T;.;.;.;.;.;.;.;.
Polyphen		0.0050	B;.;B;.;.;B;.;B;.;.;.
Vest4		0.43
MutPred		0.074		Loss of ubiquitination at K756 (P = 0.0935);.;Loss of ubiquitination at K756 (P = 0.0935);.;.;Loss of ubiquitination at K756 (P = 0.0935);.;Loss of ubiquitination at K756 (P = 0.0935);.;.;.;
MVP		0.61
MPC		0.50
ClinPred		0.34	T
GERP RS		3.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.056
gMVP		0.23

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554815021; hg19: chr9-135778107;