2-178681179-G-C
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Variant summary
Our verdict is Likely benign. Variant got -2 ACMG points: 0P and 2B. BP4_Moderate
The NM_001267550.2(TTN):c.33248-8C>G variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000044 in 1,590,632 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).
Frequency
Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)
Exomes 𝑓: 0.0000035 ( 0 hom. )
Consequence
TTN
NM_001267550.2 splice_region, splice_polypyrimidine_tract, intron
NM_001267550.2 splice_region, splice_polypyrimidine_tract, intron
Scores
2
Splicing: ADA: 0.5844
2
Clinical Significance
Conservation
PhyloP100: 0.473
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]
TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]
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ACMG classification
Classification made for transcript
Verdict is Likely_benign. Variant got -2 ACMG points.
BP4
Computational evidence support a benign effect (BayesDel_noAF=-0.34).
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.33248-8C>G | splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant | ENST00000589042.5 | NP_001254479.2 | |||
| LOC124906100 | XR_007087318.1 | n.2186-32575G>C | intron_variant, non_coding_transcript_variant |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000589042.5 | c.33248-8C>G | splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant | 5 | NM_001267550.2 | ENSP00000467141 | P1 | |||
| TTN-AS1 | ENST00000659121.1 | n.503-53325G>C | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes 0.0000132 AC: 2AN: 151900Hom.: 0 Cov.: 32
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GnomAD3 exomes AF: 0.0000175 AC: 4AN: 229144Hom.: 0 AF XY: 0.00000805 AC XY: 1AN XY: 124270
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GnomAD4 exome AF: 0.00000348 AC: 5AN: 1438732Hom.: 0 Cov.: 30 AF XY: 0.00000140 AC XY: 1AN XY: 715226
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GnomAD4 genome 0.0000132 AC: 2AN: 151900Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0AN XY: 74206
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ClinVar
Significance: Uncertain significance
Submissions summary: Uncertain:7Benign:1
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 | Jan 08, 2016 | The c.29516-8C>G variant in TTN has not been previously reported in individuals with cardiomyopathy, but has been identified in 1/10114 Latino chromosomes by th e Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org). This vari ant is located in the 3' splice region. Computational tools do not suggest an im pact to splicing. However, this information is not predictive enough to rule out pathogenicity. In summary, the clinical significance of the c.29516-8C>G varian t is uncertain. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Jan 13, 2018 | This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. - |
Dilated cardiomyopathy 1G Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Jan 13, 2018 | This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. - |
Early-onset myopathy with fatal cardiomyopathy Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Jan 13, 2018 | This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. - |
not provided Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Eurofins Ntd Llc (ga) | Nov 18, 2015 | - - |
Tibial muscular dystrophy Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Jan 13, 2018 | This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. - |
Myopathy, myofibrillar, 9, with early respiratory failure Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Jan 13, 2018 | This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. - |
TTN-related disorder Benign:1
| Likely benign, no assertion criteria provided | clinical testing | PreventionGenetics, part of Exact Sciences | May 22, 2023 | This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). - |
Computational scores
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Name
Calibrated prediction
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BayesDel_noAF
Benign
CADD
Benign
DANN
Benign
Splicing
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Calibrated prediction
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dbscSNV1_ADA
Benign
dbscSNV1_RF
Benign
SpliceAI score (max)
Details are displayed if max score is > 0.2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at