2-178636764-C-A

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PVS1PM2PP5

The NM_001267550.2(TTN):c.40963G>T(p.Glu13655*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000311 in 1,606,182 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 Conflicting classifications of pathogenicity (no stars). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

TTN
NM_001267550.2 stop_gained

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:5U:2

Conservation

PhyloP100: 7.86

Publications

6 publications found

Variant links:

Genes affected

TTN (HGNC:12403): (titin) This gene encodes a large abundant protein of striated muscle. The product of this gene is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. An N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere, respectively, so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Alternative splicing of this gene results in multiple transcript variants. Considerable variability exists in the I-band, the M-line and the Z-disc regions of titin. Variability in the I-band region contributes to the differences in elasticity of different titin isoforms and, therefore, to the differences in elasticity of different muscle types. Mutations in this gene are associated with familial hypertrophic cardiomyopathy 9, and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma. [provided by RefSeq, Feb 2012]

TTN links:

TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]

TTN-AS1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 11 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 2-178636764-C-A is Pathogenic according to our data. Variant chr2-178636764-C-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 167788.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.40963G>T	p.Glu13655*	stop_gained	Exon 225 of 363	ENST00000589042.5	NP_001254479.2	A0A0A0MTS7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.40963G>T	p.Glu13655*	stop_gained	Exon 225 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152022

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000197

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000408

AC:

AN:

244824

AF XY:

0.00

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000138

AC:

AN:

1454160

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

722460

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33056

American (AMR)

AF:

0.0000453

AC:

AN:

44136

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25844

East Asian (EAS)

AF:

0.00

AC:

AN:

39446

South Asian (SAS)

AF:

0.00

AC:

AN:

85552

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53204

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5720

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1107208

Other (OTH)

AF:

0.00

AC:

AN:

59994

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.550

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152022

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74230

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41418

American (AMR)

AF:

0.000197

AC:

AN:

15252

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5170

South Asian (SAS)

AF:

0.00

AC:

AN:

4820

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10604

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67974

Other (OTH)

AF:

0.00

AC:

AN:

2088

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.542

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00000450

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:5Uncertain:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Pathogenic:1Uncertain:2

May 27, 2025

GeneDx

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Located in a specific region of the I-band within TTN for which truncating variants are significantly associated with autosomal dominant cardiomyopathy and also with autosomal recessive skeletal myopathies (PMID: 27625338, 27869827, 32778822); Not observed at significant frequency in large population cohorts (gnomAD); Reported as an incidental finding in a cohort of individuals undergoing clinical exome sequencing; additional clinical detail was not provided (PMID: 33226272); This variant is associated with the following publications: (PMID: 33226272, 27625338, 27869827, 32778822) -

Feb 18, 2021

Revvity Omics, Revvity

Significance:Uncertain significance

Review Status:flagged submission

Collection Method:clinical testing

- -

Dec 22, 2015

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Cardiovascular phenotype

Pathogenic:2

Jan 06, 2023

Ambry Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.E4590* variant (also known as c.13768G>T), located in coding exon 52 of the TTN gene, results from a G to T substitution at nucleotide position 13768. This changes the amino acid from a glutamic acid to a stop codon within coding exon 52. This exon is located in the I-band region of the N2-B isoform of the titin protein and is constitutively expressed in TTN transcripts (percent spliced in or PSI 100%). This alteration has been reported in a subject referred for exome sequencing, but specific clinical information was limited (Connell PS et al. Circ Genom Precis Med, 2021 Feb;14:e003131). This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. While truncating variants in TTN are present in 1-3% of the general population, truncating variants in the A-band are the most common cause of dilated cardiomyopathy (DCM) (Herman DS et al. N. Engl. J. Med., 2012 Feb;366:619-28; Roberts AM et al. Sci Transl Med, 2015 Jan;7:270ra6). TTN truncating variants encoded in constitutive exons (PSI >90%) have been found to be significantly associated with DCM regardless of their position in titin (Schafer S et al. Nat. Genet., 2017 01;49:46-53). As such, this alteration is classified as likely pathogenic. -

Feb 16, 2024

Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

PVS1, PM2, PP5 -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G

Pathogenic:1

Dec 17, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Glu13655*) in the TTN gene. While this is not anticipated to result in nonsense mediated decay, it is expected to create a truncated TTN protein. This variant is present in population databases (rs727504198, gnomAD 0.006%). This premature translational stop signal has been observed in individual(s) with autosomal dominant dilated cardiomyopathy and clinical features of autosomal recessive centronuclear myopathy (internal data). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 167788). This variant is located in the I band of TTN (PMID: 25589632). Truncating variants in this region have been reported in individuals affected with autosomal recessive centronuclear myopathy (PMID: 23975875, internal data). Truncating variants in this region have also been identified in individuals affected with autosomal dominant dilated cardiomyopathy and/or cardio-related conditions (PMID: 27869827, 32964742, internal data). For these reasons, this variant has been classified as Pathogenic. -

Early-onset myopathy with fatal cardiomyopathy

Pathogenic:1

Oct 19, 2023

Baylor Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.56

BayesDel_noAF

Pathogenic

0.65

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

0.93

FATHMM_MKL

Pathogenic

0.99

PhyloP100

7.9

Vest4

0.84

GERP RS

5.9

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over