rs727503628
Positions:
Variant summary
Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1PM2
The NM_001267550.2(TTN):c.44400del(p.Lys14801ArgfsTer3) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★★). 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: 0.379
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 10 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;
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
TTN | NM_001267550.2 | c.44400del | p.Lys14801ArgfsTer3 | frameshift_variant | 240/363 | ENST00000589042.5 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
TTN | ENST00000589042.5 | c.44400del | p.Lys14801ArgfsTer3 | frameshift_variant | 240/363 | 5 | NM_001267550.2 | P1 | |
TTN-AS1 | ENST00000659121.1 | n.502+31646del | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes ? Cov.: 32
GnomAD3 genomes
?
Cov.:
32
GnomAD4 exome Cov.: 30
GnomAD4 exome
Cov.:
30
GnomAD4 genome ? Cov.: 32
GnomAD4 genome
?
Cov.:
32
ClinVar
Significance: Uncertain significance
Submissions summary: Uncertain:2
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
not specified Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Jul 03, 2014 | Variant classified as Uncertain Significance - Favor Pathogenic. The Lys12233fs variant in TTN has not been previously reported in individuals with cardiomyopat hy. Data from large studies is insufficient to assess its frequency in the gener al population. This variant is predicted to cause a frameshift, which alters the protein?s amino acid sequence beginning at position 12233 and leads to a premat ure termination codon 3 amino acids downstream. Frameshift and other truncating variants in TTN are strongly associated with DCM, particularly if they are locat ed in the exons encoding for the A-band region of the protein (Herman 2012, Pugh 2014). Variants in the I-band, where the Lys12233fs variant is located, occur a t a greater frequency in controls than in individuals with DCM (Pugh 2014). This decreases the likelihood, but does not rule out that this variant has a role in disease. In summary, while there is some suspicion for a pathogenic role based on the severity of the predicted impact to the protein, the clinical significanc e of the Lys12233Argfs variant is uncertain. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Invitae | May 23, 2019 | This variant is located in the I band of TTN (PMID: 25589632). Truncating variants in this region have been shown to be highly prevalent in the general population and unaffected individuals (PMID: 26701604, 22335739). However, truncating variants in this region have also been reported in individuals affected with autosomal recessive centronuclear myopathy (PMID: 23975875). 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. This variant has not been reported in the literature in individuals with TTN-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change results in a premature translational stop signal in the TTN gene (p.Lys14801Argfs*3). While this is not anticipated to result in nonsense mediated decay, it is expected to create a truncated TTN protein. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
Splicing
Name
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