2-178784159-C-T
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Variant summary
Our verdict is Likely benign. Variant got -4 ACMG points: 1P and 5B. PP2BP4_StrongBP6
The NM_001267550.2(TTN):c.2686G>A(p.Val896Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000182 in 1,614,128 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/18 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 0.00023 ( 0 hom., cov: 32)
Exomes 𝑓: 0.00018 ( 0 hom. )
Consequence
TTN
NM_001267550.2 missense
NM_001267550.2 missense
Scores
17
Clinical Significance
Conservation
PhyloP100: 0.543
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_benign. Variant got -4 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=0.016604513).
BP6
Variant 2-178784159-C-T is Benign according to our data. Variant chr2-178784159-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 46839.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=6, Uncertain_significance=10}.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.2686G>A | p.Val896Ile | missense_variant | 16/363 | ENST00000589042.5 | NP_001254479.2 | |
| TTN | NM_133379.5 | c.2686G>A | p.Val896Ile | missense_variant | 16/46 | ENST00000360870.10 | NP_596870.2 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000589042.5 | c.2686G>A | p.Val896Ile | missense_variant | 16/363 | 5 | NM_001267550.2 | ENSP00000467141.1 | ||
| TTN | ENST00000360870.10 | c.2686G>A | p.Val896Ile | missense_variant | 16/46 | 5 | NM_133379.5 | ENSP00000354117.4 |
Frequencies
GnomAD3 genomes 0.000230 AC: 35AN: 152168Hom.: 0 Cov.: 32
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GnomAD3 exomes AF: 0.000203 AC: 51AN: 251120Hom.: 0 AF XY: 0.000206 AC XY: 28AN XY: 135692
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GnomAD4 exome AF: 0.000176 AC: 258AN: 1461842Hom.: 0 Cov.: 31 AF XY: 0.000172 AC XY: 125AN XY: 727230
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GnomAD4 genome 0.000230 AC: 35AN: 152286Hom.: 0 Cov.: 32 AF XY: 0.000188 AC XY: 14AN XY: 74468
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ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Uncertain:10Benign:6
Revision: criteria provided, conflicting classifications
LINK: link
Submissions by phenotype
not provided Uncertain:4
| Uncertain significance, criteria provided, single submitter | clinical testing | Mayo Clinic Laboratories, Mayo Clinic | Nov 27, 2023 | BP4 - |
| Uncertain significance, criteria provided, single submitter | clinical testing | Revvity Omics, Revvity | Oct 10, 2023 | - - |
| Uncertain significance, criteria provided, single submitter | clinical testing | Eurofins Ntd Llc (ga) | Dec 22, 2015 | - - |
| Uncertain significance, criteria provided, single submitter | clinical testing | CeGaT Center for Human Genetics Tuebingen | Feb 01, 2023 | TTN: PM2, BP4 - |
not specified Benign:3
| Likely benign, criteria provided, single submitter | clinical testing | GeneDx | Mar 12, 2018 | This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. - |
| Likely benign, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Jul 23, 2015 | p.Val896Ile in exon 16 of TTN: This variant is not expected to have clinical sig nificance due to a lack of conservation across species, including mammals. Of no te, several mammals have isoleucine (Ile) at this position despite high nearby a mino acid conservation. This variant has been identified in 8/16510 South Asian chromosomes and 5/10404 African chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs376768790). - |
| Likely benign, criteria provided, single submitter | clinical testing | Women's Health and Genetics/Laboratory Corporation of America, LabCorp | May 18, 2023 | Variant summary: TTN c.2686G>A (p.Val896Ile) results in a conservative amino acid change located near Z-disk region of the encoded protein sequence. Five of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.0002 in 251120 control chromosomes, predominantly at a frequency of 0.00056 within the South Asian subpopulation in the gnomAD database. The observed variant frequency within South Asian control individuals in the gnomAD database is approximately 1.4-fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Dilated Cardiomyopathy phenotype (0.00039), strongly suggesting that the variant is a benign polymorphism found primarily in populations of South Asian origin. To our knowledge, no occurrence of c.2686G>A in individuals affected with Dilated Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Nine ClinVar submitters (evaluation after 2014) have reported the variant with conflicting assessments: 4 classify the variant as likely benign, and 5 classify the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as likely benign. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Apr 27, 2017 | This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. - |
TTN-related disorder Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | PreventionGenetics, part of Exact Sciences | Feb 20, 2023 | The TTN c.2686G>A variant is predicted to result in the amino acid substitution p.Val896Ile. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.056% of alleles in individuals of South Asian descent in gnomAD (http://gnomad.broadinstitute.org/variant/2-179648886-C-T). Although we suspect that this variant may be benign, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. - |
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 03, 2016 | - - |
Dilated cardiomyopathy 1G Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Apr 27, 2017 | This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. - |
Cardiomyopathy Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario | Oct 05, 2015 | - - |
Early-onset myopathy with fatal cardiomyopathy Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Apr 27, 2017 | This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. - |
Tibial muscular dystrophy Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Apr 27, 2017 | This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. - |
Myopathy, myofibrillar, 9, with early respiratory failure Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Apr 27, 2017 | This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. - |
Cardiovascular phenotype Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Ambry Genetics | Mar 19, 2019 | This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. - |
Computational scores
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Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
BayesDel_addAF
Benign
T
BayesDel_noAF
Benign
CADD
Benign
DANN
Benign
Eigen
Benign
Eigen_PC
Benign
FATHMM_MKL
Benign
N
LIST_S2
Benign
T;T;T;.;T;T;T;T
M_CAP
Benign
D
MetaRNN
Benign
T;T;T;T;T;T;T;T
MetaSVM
Benign
T
PrimateAI
Benign
T
PROVEAN
Benign
N;N;.;.;N;N;.;N
REVEL
Benign
Sift
Benign
T;T;.;.;T;T;.;T
Sift4G
Benign
.;.;.;.;.;.;.;T
Polyphen
0.0
.;.;.;B;.;.;B;B
Vest4
MVP
MPC
0.068
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