2-178567240-C-T
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Variant summary
Our verdict is Benign. Variant got -8 ACMG points: 1P and 9B. PP2BP4_StrongBP6BS2
The NM_001267550.2(TTN):c.78892G>A(p.Gly26298Arg) variant causes a missense change. The variant allele was found at a frequency of 0.000291 in 1,607,864 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Genomes: 𝑓 0.00035 ( 0 hom., cov: 33)
Exomes 𝑓: 0.00029 ( 2 hom. )
Consequence
TTN
NM_001267550.2 missense
NM_001267550.2 missense
Scores
2
7
8
Clinical Significance
Conservation
PhyloP100: 4.86
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 Benign. Variant got -8 ACMG points.
PP2
Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TTN. . Gene score misZ -1.1021 (greater than the threshold 3.09). Trascript score misZ 6.9794 (greater than threshold 3.09). GenCC has associacion of gene with dilated cardiomyopathy, tibial muscular dystrophy, early-onset myopathy with fatal cardiomyopathy, autosomal recessive centronuclear myopathy, hypertrophic cardiomyopathy, hypertrophic cardiomyopathy 9, TTN-related myopathy, dilated cardiomyopathy 1G, arrhythmogenic right ventricular cardiomyopathy, myopathy, myofibrillar, 9, with early respiratory failure, familial isolated dilated cardiomyopathy, childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome, autosomal recessive limb-girdle muscular dystrophy type 2J.
BP4
Computational evidence support a benign effect (MetaRNN=0.052323073).
BP6
Variant 2-178567240-C-T is Benign according to our data. Variant chr2-178567240-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47368.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, Uncertain_significance=6, Benign=4}. Variant chr2-178567240-C-T is described in Lovd as [Likely_benign].
BS2
High Homozygotes in GnomAdExome4 at 2 AD,AR gene
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.78892G>A | p.Gly26298Arg | missense_variant | 326/363 | ENST00000589042.5 | NP_001254479.2 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000589042.5 | c.78892G>A | p.Gly26298Arg | missense_variant | 326/363 | 5 | NM_001267550.2 | ENSP00000467141.1 |
Frequencies
GnomAD3 genomes 0.000349 AC: 53AN: 152068Hom.: 0 Cov.: 33
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GnomAD3 exomes AF: 0.000349 AC: 85AN: 243814Hom.: 1 AF XY: 0.000303 AC XY: 40AN XY: 132114
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GnomAD4 exome AF: 0.000285 AC: 415AN: 1455796Hom.: 2 Cov.: 37 AF XY: 0.000293 AC XY: 212AN XY: 723582
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GnomAD4 genome 0.000349 AC: 53AN: 152068Hom.: 0 Cov.: 33 AF XY: 0.000363 AC XY: 27AN XY: 74282
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ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Uncertain:6Benign:10
Revision: criteria provided, conflicting classifications
LINK: link
Submissions by phenotype
not provided Uncertain:2Benign:3
| Benign, criteria provided, single submitter | clinical testing | Athena Diagnostics | Jun 13, 2019 | - - |
| Likely benign, criteria provided, single submitter | clinical testing | GeneDx | May 17, 2021 | - - |
| Likely benign, criteria provided, single submitter | clinical testing | Revvity Omics, Revvity | Nov 30, 2023 | - - |
| Uncertain significance, criteria provided, single submitter | clinical testing | Eurofins Ntd Llc (ga) | Jun 29, 2018 | - - |
| Uncertain significance, criteria provided, single submitter | clinical testing | CeGaT Center for Human Genetics Tuebingen | Oct 01, 2024 | - - |
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. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Labcorp Genetics (formerly Invitae), Labcorp | Sep 18, 2017 | - - |
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 specified Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Apr 02, 2020 | The p.Gly23730Arg variant in TTN is classified as likely benign because it has been identified in 0.3% (25/9884) of Ashkenazi Jewish chromosomes and 0.05% (59/125924) of European chromosomes, including 1 homozygote, by gnomAD (http://gnomad.broadinstitute.org). This variant has been identified in our laboratory in 4 individuals with hypertrophic cardiomyopathy (HCM); for 2 of these individuals, a pathogenic variant in another HCM causing gene was identified that explains the clinical presentation. ACMG/AMP Criteria applied: BS1, BP5. - |
TTN-related disorder Benign:1
| Likely benign, no assertion criteria provided | clinical testing | PreventionGenetics, part of Exact Sciences | Feb 02, 2024 | 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). - |
Cardiomyopathy Benign:1
| Benign, criteria provided, single submitter | clinical testing | CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario | Sep 30, 2021 | - - |
Premature ventricular contraction Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Center for Advanced Laboratory Medicine, UC San Diego Health, University of California San Diego | Mar 25, 2019 | - - |
Myopathy, myofibrillar, 9, with early respiratory failure Benign:1
| Benign, 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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. - |
Tibial muscular dystrophy Benign:1
| Benign, 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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. - |
Cardiovascular phenotype Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Ambry Genetics | Apr 21, 2020 | In silico models in agreement (benign);Subpopulation frequency in support of benign classification - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
AlphaMissense
Pathogenic
BayesDel_addAF
Benign
T
BayesDel_noAF
Benign
CADD
Benign
DANN
Benign
Eigen
Uncertain
Eigen_PC
Uncertain
FATHMM_MKL
Uncertain
D
LIST_S2
Uncertain
D;D;D;.;D;D;D
M_CAP
Benign
D
MetaRNN
Benign
T;T;T;T;T;T;T
MetaSVM
Benign
T
MutationAssessor
Uncertain
.;.;.;M;.;.;M
PrimateAI
Uncertain
T
PROVEAN
Pathogenic
D;D;.;.;D;D;.
REVEL
Uncertain
Sift
Benign
D;T;.;.;T;T;.
Polyphen
0.98
.;.;.;D;.;.;D
Vest4
MutPred
0.50
.;.;.;Loss of catalytic residue at V24658 (P = 0.0239);.;.;Loss of catalytic residue at V24658 (P = 0.0239);
MVP
MPC
0.45
ClinPred
T
GERP RS
Splicing
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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