chr2-178736076-T-G
Variant summary
Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PVS1_ModeratePM2PP3_StrongPP5
The NM_001267550.2(TTN):c.14372-2A>C variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Genomes: not found (cov: 32)
Consequence
TTN
NM_001267550.2 splice_acceptor
NM_001267550.2 splice_acceptor
Scores
5
1
1
Splicing: ADA: 1.000
2
Clinical Significance
Conservation
PhyloP100: 8.02
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 Likely_pathogenic. Variant got 9 ACMG points.
PVS1
?
Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.0052141217 fraction of the gene. Cryptic splice site detected, with MaxEntScore 9.2, offset of 28, new splice context is: ccaccaacctttctctccAGacc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
PM2
?
Very rare variant in population databases, with high coverage;
PP3
?
Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
PP5
?
Variant 2-178736076-T-G is Pathogenic according to our data. Variant chr2-178736076-T-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 501771.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
TTN | NM_001267550.2 | c.14372-2A>C | splice_acceptor_variant | ENST00000589042.5 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
TTN | ENST00000589042.5 | c.14372-2A>C | splice_acceptor_variant | 5 | NM_001267550.2 | P1 | |||
TTN-AS1 | ENST00000659121.1 | n.773+204T>G | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes ? Cov.: 32
GnomAD3 genomes
?
Cov.:
32
GnomAD4 exome Cov.: 35
GnomAD4 exome
Cov.:
35
GnomAD4 genome ? Cov.: 32
GnomAD4 genome
?
Cov.:
32
ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Pathogenic:1Uncertain:1
Revision: criteria provided, conflicting classifications
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 | Jul 14, 2023 | This variant is not present in population databases (gnomAD no frequency). This sequence change affects an acceptor splice site in intron 49 of the TTN gene. While this is not anticipated to result in nonsense mediated decay, it is expected to create a truncated TTN protein. Disruption of this splice site has been observed in individual(s) with autosomal recessive TTN-related conditions (PMID: 27868403). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 501771). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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 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
Uncertain significance, criteria provided, single submitter | clinical testing | Eurofins Ntd Llc (ga) | May 08, 2017 | - - |
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
Pathogenic
D
MutationTaster
Benign
D;D;D;D;D;D
GERP RS
Splicing
Name
Calibrated prediction
Score
Prediction
dbscSNV1_ADA
Pathogenic
dbscSNV1_RF
Pathogenic
SpliceAI score (max)
Details are displayed if max score is > 0.2
DS_AG_spliceai
Position offset: 49
DS_AL_spliceai
Position offset: -2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at