1-201359217-C-T

Position:

chr1-201359217-C-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_StrongPP5_Very_Strong

The NM_001276345.2(TNNT2):c.890G>A(p.Trp297Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000435 in 1,610,032 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 Likely pathogenic (★★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000041 ( 0 hom. )

Consequence

TNNT2
NM_001276345.2 stop_gained

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:16

Conservation

PhyloP100: 2.38

Variant links:

Genes affected

TNNT2 (HGNC:11949): (troponin T2, cardiac type) This gene encodes the cardiac isoform of troponin T. The encoded protein is the tropomyosin-binding subunit of the troponin complex, which is located on the thin filament of striated muscles and regulates muscle contraction in response to alterations in intracellular calcium ion concentration. Mutations in this gene have been associated with familial hypertrophic cardiomyopathy as well as with dilated cardiomyopathy. [provided by RefSeq, May 2022]

TNNT2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 12 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 5 pathogenic variants in the truncated region.

PP5

Variant 1-201359217-C-T is Pathogenic according to our data. Variant chr1-201359217-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 177636.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-201359217-C-T is described in Lovd as [Likely_pathogenic]. Variant chr1-201359217-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TNNT2	NM_001276345.2 linkuse as main transcript	c.890G>A	p.Trp297Ter	stop_gained	17/17	ENST00000656932.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TNNT2	ENST00000656932.1 linkuse as main transcript	c.890G>A	p.Trp297Ter	stop_gained	17/17		NM_001276345.2	A2	P45379-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152184

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000413

AC:

AN:

242296

Hom.:

AF XY:

0.00

AC XY:

AN XY:

130664

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000296

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000412

AC:

AN:

1457848

Hom.:

Cov.:

AF XY:

0.00000414

AC XY:

AN XY:

724570

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000226

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:

0.00000360

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152184

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74328

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000378

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:16

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Pathogenic:5

Likely pathogenic, criteria provided, single submitter	clinical testing	AiLife Diagnostics, AiLife Diagnostics	Oct 12, 2021	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Mar 01, 2022	Reported to segregate with disease in two families, but no details were provided (Brito et al., 2012); Not observed at significant frequency in large population cohorts (gnomAD); Nonsense variant predicted to result in protein truncation as the last two amino acids are lost, although loss-of-function variants have not been reported downstream of this position in the protein; Limited functional studies using human induced pluripotent stem cell-derived cardiomyocytes suggest that this variant impacts protein function (Pettinato et al., 2020); however additional studies are needed to validate the functional effect of this variant in vivo; This variant is associated with the following publications: (PMID: 12707239, 27532257, 20439259, 23396983, 25351510, 26936621, 22857948, 20031601, 30297972, 33025817, 30975432) -
Likely pathogenic, no assertion criteria provided	clinical testing	Stanford Center for Inherited Cardiovascular Disease, Stanford University	Jan 16, 2012	Note this variant was found in clinical genetic testing performed by one or more labs who may also submit to ClinVar. Thus any internal case data may overlap with the internal case data of other labs. The interpretation reviewed below is that of the Stanford Center for Inherited Cardiovascular Disease. p.Trp287Stop (c.860 G>A, W287X) in TNNT2. Given strong case data, absence in controls, and segregation in multiple families, (all reviewed below) we consider this variant likely disease causing. The variant has been seen in at least 14 unrelated cases of HCM (not including the patient's family). There is weak segregation data in at least 6 families. Brito et al (2012) observed the variant in 3 of 77 unrelated individuals with HCM in their Portuguese cohort. Two of these patients have affected relatives and the authors note the variant segregated with disease however they do not provide details on the number of affected relatives with the variant. Richard et al (2003) observed the variant in 2 unrelated patients in their cohort of 197 HCM patients from France (likely redundant with Gandjbackhch et al 2010 from the same group). Bill McKenna's group observed the variant in 1 out of 223 HCM patients from their UK cohort (Lopes et al 2013). GeneDx shared they've seen it in one patient tested for HCM (presumably this family) and two tested with a DCM panel. I have requested phenotype and ancestry data. A genetic testing lab shared with us that they have seen the variant in multiple patients with HCM with segregation in some families. Of note, most of these cases were Portuguese. The variant affects one of the last residues in the protein, though it is a bit unclear how far to the end (the labs and papers conflict). The testing lab reports we have do not provide the transcript they used. Per another source, this affects the second last residue of the protein, creating a stop codon where there would normally be a tryptohan. It would lead to loss of the last two amino acids. Unlike nonsense variants that occur earlier in the amino acid sequence this variant would most likely not lead to nonsense-mediate mRNA decay. Notably, the end of the protein is highly conserved across mammals In total the variant has not been seen in ~6400 published controls and individuals from publicly available population datasets. The variant is not listed in the NHLBI Exome Sequencing Project dataset, which currently includes variant calls on 6300 Caucasian and African American individuals (as of February 18th, 2014). It is also not listed in dbSNP. The variant was not observed in 100 healthy adults analyzed by Richard et al (2003). Unfortunately there are not any Portuguese controls available. -
Likely pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Likely pathogenic, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -

Hypertrophic cardiomyopathy 2

Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Genomic Medicine Lab, University of California San Francisco	Sep 14, 2023	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory of Genetics and Molecular Cardiology, University of São Paulo	-	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Apr 11, 2023	- -

Dilated cardiomyopathy 1D;C1861864:Hypertrophic cardiomyopathy 2;C2676271:Cardiomyopathy, familial restrictive, 3

Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 11, 2024	This sequence change creates a premature translational stop signal (p.Trp287*) in the TNNT2 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 2 amino acid(s) of the TNNT2 protein. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This premature translational stop signal has been observed in individuals with hypertrophic cardiomyopathy (PMID: 12707239, 20439259, 22857948, 23396983). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 177636). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Aug 01, 2021	- -

Dilated cardiomyopathy 1D

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Apr 11, 2023

- -

Cardiomyopathy

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Jun 06, 2023

- -

Cardiomyopathy, familial restrictive, 3

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Apr 11, 2023

- -

Primary familial hypertrophic cardiomyopathy

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute

Apr 11, 2016

- -

Hypertrophic cardiomyopathy

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

May 12, 2021

The p.Trp287X variant in TNNT2 has been identified in >20 individuals with HCM and segregated with disease in 7 affected relatives from 6 families (Richard 2003 PMID: 12707239, Gandjbakhch 2010 PMID: 20439259, Brito 2012 PMID: 22857948, D. Brito pers comm, GeneDx pers comm; LMM data). Adult patients who carried this variant were noted to have mild to moderate HCM and ECG abnormalities (D. Brito pers comm). In addition, the p.Trp278X variant has been identified in 0.003% (1/32874) of Latino chromosomes by gnomAD (http://gnomad.broadinstitute.org). This nonsense variant leads to a premature termination codon at position 287. This alteration occurs within the last exon and may therefore escape nonsense mediated decay (NMD), resulting in a truncated protein that is lacking the last 2 amino acids. In summary, this variant meets our criteria to be classified as pathogenic for HCM in an autosomal dominant manner based upon case observations and segregation studies. ACMG/AMP Criteria applied: PS4, PP1_Strong, PM2_Supporting, PM4_Supporting. -

Cardiovascular phenotype

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 13, 2023

The p.W287* variant (also known as c.860G>A), located in coding exon 15 of the TNNT2 gene, results from a G to A substitution at nucleotide position 860. This changes the amino acid from a tryptophan to a stop codon within coding exon 15. This alteration has been detected in multiple hypertrophic cardiomyopathy (HCM) cohorts and has been reported to segregate with disease, but segregation details were limited (Richard P et al. Circulation, 2003 May;107:2227-32; Brito D et al. Rev Port Cardiol, 2012 Sep;31:577-87; Lopes LR et al. J. Med. Genet., 2013 Apr;50:228-39; Bales ND et al. Pediatr Cardiol, 2016 Jun;37:845-51; Walsh R et al. Genet. Med., 2017 02;19:192-203). This allele was reported in one heterozygous individual in population-based cohorts in the Genome Aggregation Database (gnomAD). Although premature stop codons are typically deleterious in nature, loss of function of TNNT2 has not been clearly established as a mechanism of disease. This stop codon, however, occurs at the 3' terminus of TNNT2, is not expected to trigger nonsense-mediated mRNA decay, and removes only the last 2 amino acids of the protein. The exact functional impact of these removed amino acids is unknown at this time. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.60

BayesDel_noAF

Pathogenic

0.62

CADD

Pathogenic

DANN

Uncertain

0.99

Eigen

Pathogenic

0.77

Eigen_PC

Uncertain

0.61

FATHMM_MKL

Pathogenic

0.98

MutationTaster

Benign

1.0

D;D;D;D;D;D;D;D;D;D

Vest4

0.49

GERP RS

4.0

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over