9-132912436-A-C

Variant names:

• chr9-132912436-A-C
• rs748775797
• NM_000368.5:c.759T>G

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.759T>G​(p.His253Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,890 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. H253R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TSC1 NM_000368.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.173
• 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 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 13 uncertain in NM_000368.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.789

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC1	NM_000368.5	c.759T>G	p.His253Gln	missense_variant	Exon 9 of 23	ENST00000298552.9	NP_000359.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC1	ENST00000298552.9	c.759T>G	p.His253Gln	missense_variant	Exon 9 of 23	1	NM_000368.5	ENSP00000298552.3
TSC1	ENST00000490179.4	c.759T>G	p.His253Gln	missense_variant	Exon 10 of 24	3		ENSP00000495533.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461890 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727244

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112010

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

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:1

May 18, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces histidine, which is basic and polar, with glutamine, which is neutral and polar, at codon 253 of the TSC1 protein (p.His253Gln). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TSC1-related conditions. 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 with a negative predictive value of 95%. 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

Aug 12, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.H253Q variant (also known as c.759T>G), located in coding exon 7 of the TSC1 gene, results from a T to G substitution at nucleotide position 759. The histidine at codon 253 is replaced by glutamine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.57
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Uncertain	0.13
CADD	Benign	18
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.83	D;.;D;.;D;.;D;.;.;.;.;.;.;.;.;.;.;D;.
Eigen	Uncertain	0.32
Eigen_PC	Benign	0.21
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Uncertain	0.88	.;D;T;D;.;.;.;D;T;.;D;.;.;D;D;D;D;D;D
M_CAP	Uncertain	0.12	D
MetaRNN	Pathogenic	0.79	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.50	D
MutationAssessor	Uncertain	2.1	M;.;M;.;M;.;M;.;.;.;.;.;.;.;.;.;.;.;.
PhyloP100		0.17
PrimateAI	Pathogenic	0.84	D
PROVEAN	Pathogenic	-6.7	D;D;D;.;.;.;.;.;.;.;.;.;.;.;.;.;.;D;.
REVEL	Pathogenic	0.69
Sift	Uncertain	0.0010	D;D;D;.;.;.;.;.;.;.;.;.;.;.;.;.;.;D;.
Sift4G	Uncertain	0.0050	D;D;D;.;.;.;.;.;.;.;.;.;.;.;.;.;.;D;.
Polyphen		1.0	D;.;D;.;D;.;D;.;.;.;.;D;D;D;.;.;.;D;.
Vest4		0.54
MutPred		0.59		Gain of catalytic residue at H253 (P = 0.016);.;Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);.;.;Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);Gain of catalytic residue at H253 (P = 0.016);.;Gain of catalytic residue at H253 (P = 0.016);.;
MVP		0.92
MPC		0.66
ClinPred		0.73	D
GERP RS		0.72
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.80
gMVP		0.59
Mutation Taster		=36/64	disease causing

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

Other links and lift over

dbSNP: rs748775797; hg19: chr9-135787823;