rs971618751
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Variant summary
Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_001267550.2(TTN):βc.72826delβ(p.Thr24276LeufsTer5) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000014 in 1,425,462 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (β β ). Variant results in nonsense mediated mRNA decay.
Frequency
Genomes: not found (cov: 32)
Exomes π: 0.0000014 ( 0 hom. )
Consequence
TTN
NM_001267550.2 frameshift
NM_001267550.2 frameshift
Scores
Not classified
Clinical Significance
Conservation
PhyloP100: 2.02
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 2-178573305-GT-G is Pathogenic according to our data. Variant chr2-178573305-GT-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 520485.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.72826del | p.Thr24276LeufsTer5 | frameshift_variant | 326/363 | ENST00000589042.5 | |
TTN-AS1 | NR_038272.1 | n.2044-9260del | intron_variant, non_coding_transcript_variant |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
TTN | ENST00000589042.5 | c.72826del | p.Thr24276LeufsTer5 | frameshift_variant | 326/363 | 5 | NM_001267550.2 | P1 | |
TTN-AS1 | ENST00000659121.1 | n.417-24284del | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes ? Cov.: 32
GnomAD3 genomes
?
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32
GnomAD4 exome AF: 0.00000140 AC: 2AN: 1425462Hom.: 0 Cov.: 38 AF XY: 0.00000284 AC XY: 2AN XY: 705046
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GnomAD4 genome ? Cov.: 32
GnomAD4 genome
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32
ClinVar
Significance: Pathogenic/Likely pathogenic
Submissions summary: Pathogenic:3
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | Invitae | Oct 04, 2023 | This sequence change creates a premature translational stop signal (p.Thr24276Leufs*5) 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: 520485). 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). 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. - |
Cardiomyopathy Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario | Feb 11, 2022 | - - |
not provided Pathogenic:1
Pathogenic, criteria provided, single submitter | clinical testing | Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute | Mar 23, 2017 | - - |
Computational scores
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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