rs56404770
Positions:
Variant summary
Our verdict is Benign. Variant got -12 ACMG points: 1P and 13B. PP2BP4_StrongBP6BS1BS2
The NM_001267550.2(TTN):āc.6353T>Cā(p.Ile2118Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000928 in 1,613,952 control chromosomes in the GnomAD database, including 19 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: š 0.0050 ( 8 hom., cov: 32)
Exomes š: 0.00050 ( 11 hom. )
Consequence
TTN
NM_001267550.2 missense
NM_001267550.2 missense
Scores
1
10
5
Clinical Significance
Conservation
PhyloP100: 9.29
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=0.0073548257).
BP6
Variant 2-178775511-A-G is Benign according to our data. Variant chr2-178775511-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47297.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Uncertain_significance=1, Benign=13}. Variant chr2-178775511-A-G is described in Lovd as [Benign].
BS1
Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.005 (761/152220) while in subpopulation AFR AF= 0.0172 (715/41532). AF 95% confidence interval is 0.0162. There are 8 homozygotes in gnomad4. There are 389 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
BS2
High Homozygotes in GnomAd4 at 8 AD,AR gene
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.6353T>C | p.Ile2118Thr | missense_variant | 28/363 | ENST00000589042.5 | |
| TTN | NM_133379.5 | c.6353T>C | p.Ile2118Thr | missense_variant | 28/46 | ENST00000360870.10 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000589042.5 | c.6353T>C | p.Ile2118Thr | missense_variant | 28/363 | 5 | NM_001267550.2 | P1 | |
| TTN | ENST00000360870.10 | c.6353T>C | p.Ile2118Thr | missense_variant | 28/46 | 5 | NM_133379.5 | ||
| TTN-AS1 | ENST00000659121.1 | n.2938A>G | non_coding_transcript_exon_variant | 12/13 |
Frequencies
GnomAD3 genomes 0.00492 AC: 749AN: 152104Hom.: 7 Cov.: 32
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GnomAD3 exomes AF: 0.00120 AC: 300AN: 251036Hom.: 2 AF XY: 0.000907 AC XY: 123AN XY: 135648
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GnomAD4 exome AF: 0.000504 AC: 736AN: 1461732Hom.: 11 Cov.: 33 AF XY: 0.000421 AC XY: 306AN XY: 727154
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GnomAD4 genome 0.00500 AC: 761AN: 152220Hom.: 8 Cov.: 32 AF XY: 0.00523 AC XY: 389AN XY: 74444
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ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Uncertain:1Benign:19
Revision: criteria provided, conflicting classifications
LINK: link
Submissions by phenotype
not specified Benign:8
| Benign, no assertion criteria provided | clinical testing | Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center | - | - - |
| Benign, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Mar 02, 2012 | Ile2118Thr in exon 28 of TTN: This variant is not expected to have clinical sign ificance because it has been identified in 1.7% (63/3738) of African American ch romosomes from a broad population by the NHLBI Exome Sequencing Project (http:// evs.gs.washington.edu/EVS; dbSNP rs56404770). - |
| Benign, criteria provided, single submitter | clinical testing | Athena Diagnostics | Aug 17, 2016 | - - |
| Benign, criteria provided, single submitter | clinical testing | Genetic Services Laboratory, University of Chicago | Aug 14, 2014 | - - |
| Benign, criteria provided, single submitter | clinical testing | GeneDx | May 01, 2014 | 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. - |
| Benign, criteria provided, single submitter | research | Biesecker Lab/Clinical Genomics Section, National Institutes of Health | Jun 24, 2013 | - - |
| Benign, criteria provided, single submitter | clinical testing | Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Oct 30, 2019 | Variant summary: TTN c.6353T>C (p.Ile2118Thr) results in a non-conservative amino acid change located in the near Z-disk/I-band region of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.0012 in 251036 control chromosomes, predominantly at a frequency of 0.016 within the African or African-American subpopulation in the gnomAD database, including 2 homozygotes. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 26 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 a benign polymorphism found primarily in populations of African or African-American origin. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (x4 benign, 1x VUS). Based on the evidence outlined above, the variant was classified as benign. - |
| Benign, no assertion criteria provided | clinical testing | Clinical Genetics, Academic Medical Center | - | - - |
Cardiomyopathy Benign:2
| Benign, criteria provided, single submitter | clinical testing | Center for Advanced Laboratory Medicine, UC San Diego Health, University of California San Diego | May 23, 2018 | - - |
| Benign, criteria provided, single submitter | clinical testing | CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario | Mar 09, 2016 | - - |
Tip-toe gait Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Practice for Gait Abnormalities, David Pomarino, Competency Network Toe Walking c/o Practice Pomarino | Jan 29, 2021 | Myopathy refers to diseases that affect skeletal Muscles. These diseases attack muscle fibers, making muscles weak. Inherited myopathies are often caused by inheriting an abnormal gene mutation from a parent that causes the disease. Symptoms of congenital myopathies usually start at birth or in early childhood, but may not appear until the teen years or even later in adulthood. Congenital myopathies are somewhat unique compared with other inherited myopathies, as weakness typically affects all muscles and is often not progressive. Symptoms are: Muscle weakness, most commonly of upper arms and shoulders and thighs, muscle cramps, stiffness and spasms, fatigue with exertion and lack of energy. Our patients all walk on tiptoe, so they show similar symptoms. When we genetically test them with our toe walking panel, we find that around 90 per cent of them have a genetic variant that explains their toe walking. These can be assigned, for example, to the area of myopathies (such as variants of the COL6A3 gene), the area of hereditary neuropathies (such as variants of the KMT2C gene) or the area of metabolic diseases (such as variants of the PYGM gene). In a smaller group of patients with almost identical symptoms, no abnormality is found in the genes of our panel, but spastic paraplegia can be detected. In another small group of our toe walkers, no abnormalities can be detected in the genes analysed in our toe walking panel, nor do they suffer from spastic paraplegia, as is also the case with healthy children. In contrast to these, however, they show a tiptoe gait. These patients suffer from infantile cerebral palsy, in which toe walking can also be observed. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J Benign:1
| Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. - |
TTN-related disorder Benign:1
| Benign, no assertion criteria provided | clinical testing | PreventionGenetics, part of Exact Sciences | May 29, 2019 | This variant is classified as 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
| Benign, criteria provided, single submitter | clinical testing | Labcorp Genetics (formerly Invitae), Labcorp | Jan 31, 2024 | - - |
Dilated cardiomyopathy 1G Benign:1
| Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. - |
Early-onset myopathy with fatal cardiomyopathy Benign:1
| Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. - |
not provided Benign:1
| Benign, criteria provided, single submitter | clinical testing | ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories | Feb 08, 2022 | - - |
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. - |
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. - |
Cardiovascular phenotype Benign:1
| Benign, criteria provided, single submitter | clinical testing | Ambry Genetics | Jul 19, 2013 | This alteration is classified as benign based on a combination of the following: 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
Source:
Name
Calibrated prediction
Score
Prediction
AlphaMissense
Uncertain
BayesDel_addAF
Benign
T
BayesDel_noAF
Benign
CADD
Benign
DANN
Benign
Eigen
Pathogenic
Eigen_PC
Uncertain
FATHMM_MKL
Uncertain
D
LIST_S2
Uncertain
D;D;D;.;D;D;D;D
MetaRNN
Benign
T;T;T;T;T;T;T;T
MetaSVM
Uncertain
T
MutationTaster
Benign
D;D;N;N;N;N;N
PrimateAI
Uncertain
T
PROVEAN
Uncertain
D;D;.;.;D;D;.;D
REVEL
Uncertain
Sift
Uncertain
D;D;.;.;D;D;.;D
Sift4G
Uncertain
.;.;.;.;.;.;.;D
Polyphen
0.92, 1.0
.;.;.;P;.;.;P;D
Vest4
MVP
MPC
0.34
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