rs200726948
Positions:
Variant summary
Our verdict is Likely benign. Variant got -4 ACMG points: 1P and 5B. PP2BP4_StrongBP6
The NM_001267550.2(TTN):c.63352C>T(p.Arg21118Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000171 in 1,612,808 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 11/19 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 0.00018 ( 0 hom., cov: 32)
Exomes 𝑓: 0.00017 ( 1 hom. )
Consequence
TTN
NM_001267550.2 missense
NM_001267550.2 missense
Scores
2
8
7
Clinical Significance
Conservation
PhyloP100: 3.56
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=0.06778693).
BP6
Variant 2-178588055-G-A is Benign according to our data. Variant chr2-178588055-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47194.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=4, Uncertain_significance=8, Benign=2}.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.63352C>T | p.Arg21118Trp | missense_variant | 305/363 | ENST00000589042.5 | NP_001254479.2 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000589042.5 | c.63352C>T | p.Arg21118Trp | missense_variant | 305/363 | 5 | NM_001267550.2 | ENSP00000467141.1 |
Frequencies
GnomAD3 genomes 0.000178 AC: 27AN: 151946Hom.: 0 Cov.: 32
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GnomAD3 exomes AF: 0.000266 AC: 66AN: 247928Hom.: 0 AF XY: 0.000283 AC XY: 38AN XY: 134494
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GnomAD4 exome AF: 0.000170 AC: 249AN: 1460862Hom.: 1 Cov.: 33 AF XY: 0.000167 AC XY: 121AN XY: 726710
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GnomAD4 genome 0.000178 AC: 27AN: 151946Hom.: 0 Cov.: 32 AF XY: 0.000175 AC XY: 13AN XY: 74188
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ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Uncertain:8Benign:6
Revision: criteria provided, conflicting classifications
LINK: link
Submissions by phenotype
not provided Uncertain:3Benign:1
| Uncertain significance, criteria provided, single submitter | research | Biesecker Lab/Clinical Genomics Section, National Institutes of Health | Jun 24, 2013 | - - |
| Uncertain significance, criteria provided, single submitter | clinical testing | CeGaT Center for Human Genetics Tuebingen | Aug 01, 2019 | - - |
| Uncertain significance, criteria provided, single submitter | clinical testing | Revvity Omics, Revvity | Jul 07, 2020 | - - |
| Likely benign, criteria provided, single submitter | clinical testing | GeneDx | Nov 24, 2020 | - - |
not specified Uncertain:1Benign:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Oct 24, 2012 | The Arg18550Trp variant in TTN has not been reported in the literature nor previ ously identified by our laboratory. This variant has been identified in 1/569 ch romosomes from the ClinSeq project listed in dbSNP (rs200726948). Computational analyses (biochemical amino acid properties, conservation, AlignGVGD, PolyPhen2, and SIFT) suggest that the Arg18550Trp variant may impact the protein, though t his information is not predictive enough to determine pathogenicity. Additional studies are needed to fully assess its clinical significance. - |
| Likely benign, criteria provided, single submitter | clinical testing | Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Jun 30, 2023 | Variant summary: TTN c.55648C>T (p.Arg18550Trp) results in a non-conservative amino acid change located in the A-band domain of the encoded protein sequence. Three of four in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00027 in 247928 control chromosomes, predominantly at a frequency of 0.0012 within the East Asian subpopulation in the gnomAD database. The observed variant frequency within East Asian control individuals in the gnomAD database is approximately 3.071 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 East Asian origin. c.55648C>T has been reported in the literature in at least one individual affected with Ventricular tachycardia without evidence of causality (example: Guelly_2021). These report(s) do not provide unequivocal conclusions about association of the variant with Dilated Cardiomyopathy. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 33552729). Seven submitters have cited clinical-significance assessments for this variant to ClinVar after 2014, classifying the variant as uncertain significance (n=3), likely benign (n=3), or benign (n=1). 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 | Jan 12, 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 12, 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 12, 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. - |
Cardiovascular phenotype Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Ambry Genetics | Nov 11, 2013 | The p.R18550W variant (also known as c.55648C>T) is located in coding exon 253 of the TTN gene. This alteration results from a C to T substitution at nucleotide position 55648. The arginine at codon 18550 is replaced by tryptophan, an amino acid with dissimilar properties. This alteration was identified in 1/930 alleles (1/465 individuals) in a subset of the ClinSeq cohort that was reported in a recent publication, and authors classified this as a variant of unknown significance (Ng et al.Circ Cardiovasc Genet. 2013;6:337-346).This variant was previously reported in dbSNP asrs200726948.This variant was not reported in population-based cohorts in the 1000 Genomes Project or the NHLBI Exome Sequencing Project (ESP). In the ESP, this variant was not reported in 6145 samples (12290 alleles) with coverage at this position.Based on protein sequence alignment, this amino acid position is highly conserved in available vertebrate species.In addition, this alteration is predicted to be probably damaging by PolyPhen in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this variant remains unclear. - |
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 25, 2024 | - - |
Cardiomyopathy Benign:1
| Likely benign, criteria provided, single submitter | clinical testing | Center for Advanced Laboratory Medicine, UC San Diego Health, University of California San Diego | Sep 04, 2018 | - - |
Myopathy, myofibrillar, 9, with early respiratory failure Benign:1
| Benign, criteria provided, single submitter | clinical testing | Illumina Laboratory Services, Illumina | Jan 12, 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 12, 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. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
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
Uncertain
T
MutationAssessor
Pathogenic
.;.;.;M;.;.;M
PrimateAI
Uncertain
T
PROVEAN
Pathogenic
D;D;.;.;D;D;.
REVEL
Uncertain
Sift
Uncertain
D;D;.;.;D;D;.
Polyphen
1.0
.;.;.;D;.;.;D
Vest4
MutPred
0.53
.;.;.;Gain of catalytic residue at C19478 (P = 0.0182);.;.;Gain of catalytic residue at C19478 (P = 0.0182);
MVP
MPC
0.47
ClinPred
T
GERP RS
Splicing
Name
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Score
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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