rs764687326

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PVS1PP5

The NM_001267550.2(TTN):c.22633C>T(p.Arg7545*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000868 in 1,613,230 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 0.000013 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000082 ( 0 hom. )

Consequence

TTN
NM_001267550.2 stop_gained

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:4

Conservation

PhyloP100: -0.444

Publications

0 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: Likely_pathogenic. The variant received 9 ACMG points.

PVS1

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

PP5

Variant 2-178722030-G-A is Pathogenic according to our data. Variant chr2-178722030-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 466909.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.22633C>T	p.Arg7545*	stop_gained	Exon 78 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.22633C>T	p.Arg7545*	stop_gained	Exon 78 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152126

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:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000402

AC:

AN:

248632

AF XY:

0.00000741

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000888

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000821

AC:

AN:

1461104

Hom.:

Cov.:

AF XY:

0.0000110

AC XY:

AN XY:

726818

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33444

American (AMR)

AF:

0.00

AC:

AN:

44708

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26112

East Asian (EAS)

AF:

0.00

AC:

AN:

39688

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86168

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53386

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5760

European-Non Finnish (NFE)

AF:

0.00000900

AC:

AN:

1111498

Other (OTH)

AF:

0.0000166

AC:

AN:

60340

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.488

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152126

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74310

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41448

American (AMR)

AF:

0.00

AC:

AN:

15254

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10612

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

68000

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000712

Hom.:

Bravo

AF:

0.00000378

ExAC

AF:

0.00000827

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:4

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:3

Jan 20, 2021

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Not observed at a significant frequency in large population cohorts (Lek et al., 2016); Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a region of the TTN gene for which loss-of-function is not a well established mechanism of disease; Observed in an individual with early-onset atrial fibrillation, however, additional clinical information was not provided (Choi et al., 2018); This variant is associated with the following publications: (PMID: 30535219) -

Sep 01, 2022

CeGaT Center for Human Genetics Tuebingen

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

TTN: PVS1:Strong, PM2:Supporting -

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

The TTN p.Arg6301* variant was not identified in the literature nor was it identified in LOVD 3.0. The variant was identified in dbSNP (ID: rs764687326) and ClinVar (classified as uncertain significance by Invitae). The variant was identified in control databases in 3 of 280012 chromosomes at a frequency of 0.00001071 (Genome Aggregation Database March 6, 2019, v2.1.1). The variant was observed in the following populations: Other in 1 of 7108 chromosomes (freq: 0.000141) and European (non-Finnish) in 2 of 128018 chromosomes (freq: 0.000016), but was not observed in the African, Latino, Ashkenazi Jewish, East Asian, European (Finnish), or South Asian populations. The c.18901C>T variant leads to a premature stop codon at position 6301 which is predicted to lead to a truncated or absent protein and loss of function. Loss of function variants of the TTN gene are an established mechanism of disease in dilated cardiomyopathy (DCM), however this transcript is not highly expressed in DCM, therefore the clinical significance of this premature stop codon is not clear. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance. -

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

Pathogenic:1

Dec 17, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Arg7545*) 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 (rs764687326, gnomAD 0.003%). This premature translational stop signal has been observed in individual(s) with atrial fibrillation (PMID: 30535219). ClinVar contains an entry for this variant (Variation ID: 466909). 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). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1838244:Tibial muscular dystrophy;C1858763:Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure;C2673677:Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Sep 08, 2021

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.41

BayesDel_noAF

Pathogenic

0.45

CADD

Pathogenic

(source)

DANN

Benign

0.96

Eigen

Benign

0.10

Eigen_PC

Benign

-0.21

FATHMM_MKL

Benign

0.25

PhyloP100

-0.44

Vest4

0.90

GERP RS

-5.7

Mutation Taster

=2/198

disease causing (fs/PTC)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over