rs748111134

Variant names:

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PVS1PP5

The NM_001267550.2(TTN):c.23386C>T(p.Arg7796*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000373 in 1,608,164 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: 0.0000027 ( 0 hom. )

Consequence

TTN
NM_001267550.2 stop_gained

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:2

Conservation

PhyloP100: 1.34

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 made for transcript

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

PVS1

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

PP5

Variant 2-178720256-G-A is Pathogenic according to our data. Variant chr2-178720256-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 223348.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.23386C>T	p.Arg7796*	stop_gained	Exon 81 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.23386C>T	p.Arg7796*	stop_gained	Exon 81 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152166

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000815

AC:

AN:

245404

Hom.:

AF XY:

0.0000150

AC XY:

AN XY:

132964

show subpopulations

Gnomad AFR exome

AF:

0.0000647

Gnomad AMR exome

AF:

0.00

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:

0.00000901

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000275

AC:

AN:

1455998

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

723352

show subpopulations

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:

0.00000361

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152166

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74328

show subpopulations

Gnomad4 AFR

AF:

0.0000483

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:

0.00

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000756

ExAC

AF:

0.0000166

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

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

Pathogenic:1

Oct 28, 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.Arg7796*) 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 (rs748111134, gnomAD 0.007%). This premature translational stop signal has been observed in individual(s) with autosomal recessive congenital myopathy (PMID: 33449170). ClinVar contains an entry for this variant (Variation ID: 223348). 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. -

not provided

Uncertain:1

Jul 17, 2019

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Primary dilated cardiomyopathy

Uncertain:1

Oct 08, 2014

Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: research

This TTN truncating variant (TTNtv) was identified in one individual in this cohort and is located in an exon with intermediate levels of cardiac expression. In the seven cohorts assessed, TTNtv were found in 14% of ambulant DCM, 22% end-stage or familial DCM, and 2% controls. Heterozygous nonsense, frameshift and canonical splice-disrupting variants found in constitutive and other highly utilised exons are highly likely to be pathogenic when identified in individuals with phenotypically confirmed DCM. TTNtv found incidentally in healthy individuals (excluding familial assessment of DCM relatives) are thought to have low penetrance, particularly when identified in exons that are not constitutively expressed in the heart. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.45

BayesDel_noAF

Pathogenic

0.59

CADD

Pathogenic

DANN

Uncertain

0.98

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

0.94

FATHMM_MKL

Uncertain

0.87

Vest4

0.90

GERP RS

5.9

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.050

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