9-132902760-C-A

Position:

• chr9-132902760-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP2

The NM_000368.5(TSC1):​c.2236G>T​(p.Asp746Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,558 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: TSC1 NM_000368.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 7.48

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 3 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC1	NM_000368.5	c.2236G>T	p.Asp746Tyr	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.2236G>T	p.Asp746Tyr	missense_variant	18/23	1	NM_000368.5	ENSP00000298552	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461558 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727080

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 1 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 25, 2023	This variant is not present in population databases (gnomAD no frequency). 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: 186515). This variant has not been reported in the literature in individuals affected with TSC1-related conditions. This sequence change replaces aspartic acid, which is acidic and polar, with tyrosine, which is neutral and polar, at codon 746 of the TSC1 protein (p.Asp746Tyr). -

Tuberous sclerosis syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Sep 17, 2023

This missense variant replaces aspartic acid with tyrosine at codon 746 of the TSC1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with TSC1-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Lymphangiomyomatosis;C1846385:Isolated focal cortical dysplasia type II;C1854465:Tuberous sclerosis 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Sep 29, 2021

- -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 22, 2023

The p.D746Y variant (also known as c.2236G>T), located in coding exon 16 of the TSC1 gene, results from a G to T substitution at nucleotide position 2236. The aspartic acid at codon 746 is replaced by tyrosine, an amino acid with highly dissimilar properties. This amino acid position is well conserved in available vertebrate species. 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	0.75
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.14
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.81	D;.;D;.;.;D;.;D;.;.;.
Eigen	Pathogenic	0.68
Eigen_PC	Pathogenic	0.73
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.93	.;D;D;D;D;.;.;.;D;D;.
M_CAP	Uncertain	0.19	D
MetaRNN	Uncertain	0.63	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.24	D
MutationAssessor	Benign	1.6	L;.;L;.;.;L;.;L;.;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.53	T
PROVEAN	Pathogenic	-4.8	D;D;D;.;.;.;.;.;.;.;.
REVEL	Uncertain	0.62
Sift	Uncertain	0.0010	D;D;D;.;.;.;.;.;.;.;.
Sift4G	Uncertain	0.0060	D;D;D;.;.;.;.;.;.;.;.
Polyphen		1.0	D;.;D;.;.;D;.;D;.;.;.
Vest4		0.81
MutPred		0.24		Loss of disorder (P = 0.0188);.;Loss of disorder (P = 0.0188);.;.;Loss of disorder (P = 0.0188);.;Loss of disorder (P = 0.0188);.;.;.;
MVP		0.75
MPC		1.4
ClinPred		0.99	D
GERP RS		5.7
Varity_R		0.79
gMVP		0.60

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs786203007; hg19: chr9-135778147;