2-178718186-C-T
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Variant summary
Our verdict is Benign. Variant got -12 ACMG points: 1P and 13B. PP2BP4_StrongBP6BS1BS2
The NM_001267550.2(TTN):c.24820G>A(p.Glu8274Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00298 in 1,604,162 control chromosomes in the GnomAD database, including 10 homozygotes. In-silico tool predicts a benign outcome for this variant. 11/18 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Genomes: 𝑓 0.0023 ( 3 hom., cov: 32)
Exomes 𝑓: 0.0030 ( 7 hom. )
Consequence
TTN
NM_001267550.2 missense
NM_001267550.2 missense
Scores
6
10
Clinical Significance
Conservation
PhyloP100: 3.00
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 -12 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=0.011323154).
BP6
Variant 2-178718186-C-T is Benign according to our data. Variant chr2-178718186-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 46741.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, not_provided=1, Benign=5, Uncertain_significance=4}. Variant chr2-178718186-C-T is described in Lovd as [Likely_benign]. Variant chr2-178718186-C-T is described in Lovd as [Benign].
BS1
Variant frequency is greater than expected in population nfe. gnomad4 allele frequency = 0.00232 (354/152266) while in subpopulation NFE AF= 0.00382 (260/68012). AF 95% confidence interval is 0.00344. There are 3 homozygotes in gnomad4. There are 166 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
BS2
High Homozygotes in GnomAd4 at 3 AD,AR gene
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.24820G>A | p.Glu8274Lys | missense_variant | 86/363 | ENST00000589042.5 | NP_001254479.2 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000589042.5 | c.24820G>A | p.Glu8274Lys | missense_variant | 86/363 | 5 | NM_001267550.2 | ENSP00000467141 | P1 | |
| TTN-AS1 | ENST00000659121.1 | n.503-16318C>T | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes 0.00233 AC: 354AN: 152148Hom.: 3 Cov.: 32
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GnomAD3 exomes AF: 0.00231 AC: 558AN: 241912Hom.: 0 AF XY: 0.00228 AC XY: 301AN XY: 131786
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GnomAD4 exome AF: 0.00305 AC: 4426AN: 1451896Hom.: 7 Cov.: 35 AF XY: 0.00300 AC XY: 2169AN XY: 722490
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GnomAD4 genome 0.00232 AC: 354AN: 152266Hom.: 3 Cov.: 32 AF XY: 0.00223 AC XY: 166AN XY: 74440
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ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Uncertain:4Benign:16Other:1
Revision: criteria provided, conflicting classifications
LINK: link
Submissions by phenotype
not provided Uncertain:1Benign:6
| Benign, criteria provided, single submitter | clinical testing | GeneDx | Sep 29, 2020 | - - |
| Likely benign, no assertion criteria provided | clinical testing | Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen | - | - - |
| Likely benign, no assertion criteria provided | clinical testing | Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC) | - | - - |
| Likely benign, criteria provided, single submitter | clinical testing | CeGaT Center for Human Genetics Tuebingen | Jul 01, 2024 | TTN: BS2 - |
| Likely benign, criteria provided, single submitter | research | Biesecker Lab/Clinical Genomics Section, National Institutes of Health | Jun 24, 2013 | - - |
| Likely benign, no assertion criteria provided | clinical testing | Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center | - | - - |
| Uncertain significance, criteria provided, single submitter | clinical testing | ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories | Nov 09, 2023 | The TTN c.24820G>A; p.Glu8274Lys variant (rs72648981; ClinVar Variation ID: 46741) is rare in the general population (<1% allele frequency in the Genome Aggregation Database) and has not been reported in the medical literature in association with dilated cardiomyopathy (DCM) or other TTN-related disease. The clinical relevance of rare missense variants in this gene, which are identified on average once per individual sequenced in affected populations (Herman 2012), is not well understood. Yet, evidence suggests that the vast majority of such missense variants do not contribute to the clinical outcome of DCM (Begay 2015). Thus, the clinical significance of the p.Glu8274Lys variant cannot be determined with certainty. References: Begay RL et al. Role of Titin Missense Variants in Dilated Cardiomyopathy. J Am Heart Assoc. 2015 Nov 13;4(11). Herman DS et al. Truncations of titin causing dilated cardiomyopathy. N Engl J Med. 2012 Feb 16;366(7):619-28. Linke and Hamdani. Gigantic business: titin properties and function through thick and thin. Circ Res 2014; 114(6): 1052-1068. - |
not specified Benign:5
| Likely benign, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Mar 21, 2015 | p.Glu7030Lys in exon 83 of TTN: This variant is not expected to have clinical si gnificance because it has been identified in 0.3% (200/65878) of European chromo somes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs72648981). - |
| Likely benign, criteria provided, single submitter | clinical testing | Eurofins Ntd Llc (ga) | Nov 12, 2015 | - - |
| Benign, criteria provided, single submitter | clinical testing | Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Oct 07, 2019 | Variant summary: TTN c.21088G>A (p.Glu7030Lys) results in a conservative amino acid change located in the I-band of the encoded protein sequence. Three of four in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.0023 in 241912 control chromosomes. The observed variant frequency is approximately 3.69 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Cardiomyopathy phenotype (0.00063), strongly suggesting that the variant is benign. c.21088G>A has been reported in the literature in individuals affected with Cardiomyopathy (Lopes_2013). This report does not provide unequivocal conclusions about association of the variant with Cardiomyopathy. Co-occurrences with other pathogenic variants have been reported (MYBPC3 c.1504C>T/p.R502W; MYH7 c.2539A>G/p.K847E), providing supporting evidence for a benign role. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as likely benign. Based on the evidence outlined above, the variant was classified as benign. - |
| Benign, no assertion criteria provided | clinical testing | Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+ | - | - - |
| Benign, no assertion criteria provided | clinical testing | Clinical Genetics, Academic Medical Center | - | - - |
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. - |
TTN-related disorder Benign:1
| Likely benign, no assertion criteria provided | clinical testing | PreventionGenetics, part of Exact Sciences | Aug 25, 2021 | 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). - |
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Labcorp Genetics (formerly Invitae), Labcorp | Jan 29, 2024 | - - |
Cardiomyopathy Benign:1
| Benign, criteria provided, single submitter | clinical testing | CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario | Feb 01, 2018 | - - |
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. - |
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. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1838244:Tibial muscular dystrophy;C1858763:Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure;C2673677:Early-onset myopathy with fatal cardiomyopathy Other:1
| not provided, no classification provided | phenotyping only | GenomeConnect, ClinGen | - | Variant interpreted as Uncertain significance and reported on 09-14-2018 by Lab or GTR ID 239772. GenomeConnect assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. GenomeConnect staff make no attempt to reinterpret the clinical significance of the variant. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
BayesDel_addAF
Benign
T
BayesDel_noAF
Benign
CADD
Benign
DANN
Uncertain
Eigen
Uncertain
Eigen_PC
Uncertain
FATHMM_MKL
Uncertain
D
LIST_S2
Benign
T;T;.;T
M_CAP
Benign
D
MetaRNN
Benign
T;T;T;T
MetaSVM
Benign
T
MutationTaster
Benign
D;D;D;D;D;N
PrimateAI
Uncertain
T
PROVEAN
Uncertain
D;.;.;.
REVEL
Benign
Sift
Benign
T;.;.;.
Polyphen
0.97
.;.;D;D
Vest4
MVP
MPC
0.26
ClinPred
T
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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