rs727503547
Positions:
Variant summary
Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_001267550.2(TTN):c.94180delinsTCTAGCAG(p.Pro31394SerfsTer12) variant causes a frameshift change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.
Frequency
Genomes: not found (cov: 32)
Consequence
TTN
NM_001267550.2 frameshift
NM_001267550.2 frameshift
Scores
Not classified
Clinical Significance
Conservation
PhyloP100: 4.67
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 18 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 2-178547446-G-CTGCTAGA is Pathogenic according to our data. Variant chr2-178547446-G-CTGCTAGA is described in ClinVar as [Likely_pathogenic]. Clinvar id is 165720.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
TTN | NM_001267550.2 | c.94180delinsTCTAGCAG | p.Pro31394SerfsTer12 | frameshift_variant | 339/363 | ENST00000589042.5 | |
TTN-AS1 | NR_038272.1 | n.2043+5085delinsCTGCTAGA | intron_variant, non_coding_transcript_variant |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
TTN | ENST00000589042.5 | c.94180delinsTCTAGCAG | p.Pro31394SerfsTer12 | frameshift_variant | 339/363 | 5 | NM_001267550.2 | P1 | |
TTN-AS1 | ENST00000659121.1 | n.416+23810delinsCTGCTAGA | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes ? Cov.: 32
GnomAD3 genomes
?
Cov.:
32
GnomAD4 exome Cov.: 34
GnomAD4 exome
Cov.:
34
GnomAD4 genome ? Cov.: 32
GnomAD4 genome
?
Cov.:
32
ClinVar
Significance: Pathogenic/Likely pathogenic
Submissions summary: Pathogenic:6
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
not provided Pathogenic:2
Likely pathogenic, criteria provided, single submitter | clinical testing | AiLife Diagnostics, AiLife Diagnostics | Feb 16, 2022 | - - |
Pathogenic, criteria provided, single submitter | clinical testing | GeneDx | Aug 04, 2023 | Has not been previously published as pathogenic or benign to our knowledge; Not observed at significant frequency in large population cohorts (gnomAD); Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Located in the A-band region of TTN in which the majority of loss of function variants have been associated with autosomal dominant titinopathies (Herman et al., 2012) - |
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | Invitae | Jul 06, 2022 | This variant is not present in population databases (gnomAD no frequency). 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. This variant is located in the A band of TTN (PMID: 25589632). Truncating variants in this region are significantly overrepresented in patients affected with dilated cardiomyopathy (PMID: 25589632). Truncating variants in this region have also been reported in individuals affected with autosomal recessive centronuclear myopathy (PMID: 23975875). ClinVar contains an entry for this variant (Variation ID: 466668). This variant has not been reported in the literature in individuals affected with TTN-related conditions. This sequence change creates a premature translational stop signal (p.Pro31394Serfs*12) in the TTN gene. While this is not anticipated to result in nonsense mediated decay, it is expected to create a truncated TTN protein. - |
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 Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | Fulgent Genetics, Fulgent Genetics | Aug 19, 2021 | - - |
Primary dilated cardiomyopathy Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Jul 09, 2014 | The Pro28826fs variant in TTN has not been reported in individuals with cardiomy opathy or in large population studies. This variant is predicted to cause a fram eshift, which alters the protein?s amino acid sequence beginning at position 288 26 and lead to a premature termination codon 12 amino acids downstream. This alt eration is then predicted to lead to a truncated or absent protein. Frameshift a nd other truncating variants in TTN are strongly associated with DCM, particular ly if they are located in the exons encoding for the A-band region of the protei n (Herman 2012, Pugh 2014), where this variant is located. In summary, although additional studies are required to fully establish its clinical significance, th e Pro28826fs variant is likely pathogenic. - |
Cardiovascular phenotype Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | Ambry Genetics | Nov 30, 2021 | The c.66985delCinsTCTAGCAG variant, located in coding exon 166 of the TTN gene, results from the deletion of one nucleotide and insertion of 8 nucleotides causing a translational frameshift with a predicted alternate stop codon (p.P22329Sfs*12). This exon is located in the A-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 variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). 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. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at