9-132912436-A-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP2 PP3

The NM_000368.5(TSC1):c.759T>A(p.His253Gln) 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 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. H253P) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TSC1 NM_000368.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.173

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 Likely_pathogenic. Variant got 6 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, 14 uncertain in NM_000368.5
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, TSC1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.788

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TSC1	NM_000368.5	c.759T>A	p.His253Gln	missense_variant	9/23	ENST00000298552.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC1	ENST00000298552.9	c.759T>A	p.His253Gln	missense_variant	9/23	1	NM_000368.5	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Sep 25, 2019

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. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with TSC1-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces histidine with glutamine at codon 253 of the TSC1 protein (p.His253Gln). The histidine residue is highly conserved and there is a small physicochemical difference between histidine and glutamine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 19, 2023

The p.H253Q variant (also known as c.759T>A), located in coding exon 7 of the TSC1 gene, results from a T to A 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. Since supporting evidence is limited at this time, the clinical significance of this alteration 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
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;.;.;.;.;.;.;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D
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
Varity_R		0.80
gMVP		0.59

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: rs748775797; hg19: chr9-135787823;