rs587780490
Positions:
Variant summary
Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PVS1PM2PP5
The NM_001267550.2(TTN):c.5047C>T(p.Arg1683Ter) variant causes a stop gained change. The variant allele was found at a frequency of 0.00000205 in 1,461,792 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: not found (cov: 32)
Exomes 𝑓: 0.0000021 ( 0 hom. )
Consequence
TTN
NM_001267550.2 stop_gained
NM_001267550.2 stop_gained
Scores
4
2
1
Clinical Significance
Conservation
PhyloP100: 5.64
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]
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ACMG classification
Classification made for transcript
Verdict is Pathogenic. Variant got 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 2-178776817-G-A is Pathogenic according to our data. Variant chr2-178776817-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 130673.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=3, Pathogenic=1, Likely_pathogenic=1}.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
TTN | NM_001267550.2 | c.5047C>T | p.Arg1683Ter | stop_gained | 28/363 | ENST00000589042.5 | |
TTN | NM_133379.5 | c.5047C>T | p.Arg1683Ter | stop_gained | 28/46 | ENST00000360870.10 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
TTN | ENST00000589042.5 | c.5047C>T | p.Arg1683Ter | stop_gained | 28/363 | 5 | NM_001267550.2 | P1 | |
TTN | ENST00000360870.10 | c.5047C>T | p.Arg1683Ter | stop_gained | 28/46 | 5 | NM_133379.5 | ||
TTN-AS1 | ENST00000659121.1 | n.4244G>A | non_coding_transcript_exon_variant | 12/13 |
Frequencies
GnomAD3 genomes ? Cov.: 32
GnomAD3 genomes
?
Cov.:
32
GnomAD4 exome AF: 0.00000205 AC: 3AN: 1461792Hom.: 0 Cov.: 33 AF XY: 0.00000275 AC XY: 2AN XY: 727192
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GnomAD4 genome ? Cov.: 32
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ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Pathogenic:2Uncertain:3
Revision: criteria provided, conflicting classifications
LINK: link
Submissions by phenotype
Tibial muscular dystrophy Pathogenic:1
Pathogenic, criteria provided, single submitter | clinical testing | Genetic Services Laboratory, University of Chicago | Dec 23, 2013 | - - |
Primary dilated cardiomyopathy Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Jan 25, 2019 | The p.Arg1683X variant in TTN has not been previously reported in individuals with DCM and was absent from large population studies. This nonsense variant leads to a premature termination codon at position 1683, which is predicted to lead to a truncated or absent protein. Nonsense and other truncating variants in TTN are strongly associated with DCM if they impact the exons encoding for the A-band (Herman 2012, Pugh 2014) and/or are located in an exon that is highly expressed in the heart (Roberts 2015). The p.Arg1683X variant is located in a highly expressed exon near the Z-disk/I-band. In summary, although additional studies are required to fully establish its clinical significance, this variant meets criteria to be classified as likely pathogenic for autosomal dominant DCM. ACMG/AMP Criteria applied: PVS1, PM2. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Invitae | Sep 04, 2023 | This sequence change creates a premature translational stop signal (p.Arg1683*) 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 not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TTN-related conditions. ClinVar contains an entry for this variant (Variation ID: 130673). This variant is located in the Z band of TTN (PMID: 25589632). Variants in this region may be clinically relevant, but have not been definitively shown to cause cardiomyopathy or neuromuscular disease (PMID: 27493940, 32778822). 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. - |
not provided Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | GeneDx | Nov 22, 2022 | Not observed at significant frequency in large population cohorts (gnomAD); Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene or region of a gene for which loss of function is not a well-established mechanism of disease; Has not been previously published as pathogenic or benign to our knowledge - |
Cardiovascular phenotype Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Ambry Genetics | Dec 06, 2022 | The p.R1637* variant (also known as c.4909C>T), located in coding exon 26 of the TTN gene, results from a C to T substitution at nucleotide position 4909. This changes the amino acid from an arginine to a stop codon within coding exon 26. This exon is located in the Z-disk/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 is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. Truncating variants in the A-band of titin are the most common cause of dilated cardiomyopathy (DCM), and, regardless of their position, truncating variants encoded in constitutive exons (PSI >90%) have been found to be significantly associated with DCM (Herman DS et al. N. Engl. J. Med. 2012;366:619-28; Roberts AM et al. Sci Transl Med. 2015;7:270ra6; Schafer S et al. Nat. Genet. 2017;49:46-53). However, TTN truncating variants have also been reported in 1-3% of the general population (Herman DS et al. N. Engl. J. Med. 2012;366:619-28). Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
BayesDel_addAF
Pathogenic
D
BayesDel_noAF
Pathogenic
CADD
Pathogenic
DANN
Uncertain
Eigen
Pathogenic
Eigen_PC
Pathogenic
FATHMM_MKL
Uncertain
D
MutationTaster
Benign
A;A;A;A;A;A;A
Vest4
GERP RS
Splicing
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Calibrated prediction
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SpliceAI score (max)
Details are displayed if max score is > 0.2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at