rs142951505
Variant summary
Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PP3_Strong
The NM_001267550.2(TTN):c.3100G>A(p.Val1034Met) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000956 in 1,612,670 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_001267550.2 missense, splice_region
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Uncertain_significance. Variant got 4 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.3100G>A | p.Val1034Met | missense_variant, splice_region_variant | Exon 18 of 363 | ENST00000589042.5 | NP_001254479.2 | |
| TTN | NM_133379.5 | c.3100G>A | p.Val1034Met | missense_variant, splice_region_variant | Exon 18 of 46 | ENST00000360870.10 | NP_596870.2 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000589042.5 | c.3100G>A | p.Val1034Met | missense_variant, splice_region_variant | Exon 18 of 363 | 5 | NM_001267550.2 | ENSP00000467141.1 | ||
| TTN | ENST00000360870.10 | c.3100G>A | p.Val1034Met | missense_variant, splice_region_variant | Exon 18 of 46 | 5 | NM_133379.5 | ENSP00000354117.4 |
Frequencies
GnomAD3 genomes 0.000611 AC: 93AN: 152178Hom.: 0 Cov.: 32
GnomAD3 exomes AF: 0.000811 AC: 203AN: 250400Hom.: 1 AF XY: 0.000754 AC XY: 102AN XY: 135328
GnomAD4 exome AF: 0.000992 AC: 1448AN: 1460374Hom.: 1 Cov.: 32 AF XY: 0.000932 AC XY: 677AN XY: 726522
GnomAD4 genome 0.000611 AC: 93AN: 152296Hom.: 0 Cov.: 32 AF XY: 0.000631 AC XY: 47AN XY: 74478
ClinVar
Submissions by phenotype
not specified Uncertain:3Benign:3
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Missense variants in the TTN gene are considered 'unclassified' if they are not previously reported in the literature and do not have >1% frequency in the population to be considered a polymorphism. Research indicates that truncating mutations in the TTN gene are expected to account for approximately 25% of familial and 18% of sporadic idiopathic DCM; however, truncating variants in the TTN gene have been reported in approximately 3% of reported control alleles. There has been little investigation into non-truncating variants. (Herman D et al. Truncations of titin causing dilated cardiomyopathy. N Eng J Med 366:619-628, 2012) -
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Variant summary: TTN c.3100G>A (p.Val1034Met) results in a conservative amino acid change located in the near Z-disk region (Ig-like domain) of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. Several computational tools predict a significant impact on normal splicing: Three predict the variant abolishes a 5 splicing donor site. Two predict the variant weakens a 3 acceptor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.00081 in 250400 control chromosomes, predominantly at a frequency of 0.0011 within the Non-Finnish European subpopulation in the gnomAD database. The observed variant frequency within Non-Finnish European control individuals in the gnomAD database is approximately 2 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 Non-Finnish European origin. c.3100G>A has been reported in the literature in individuals affected with various phenotypes including end-stage dilated cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy and limb gridle muscular dystrophy (e.g. Roberts_2015, Haas_2015, Lopes_2013, Vasli_2012). These reports do not provide unequivocal conclusions about association of the variant with Cardiomyopathy. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Eleven ClinVar submitters (evaluation after 2014) cite the variant as benign (n=2), likely benign (n=2) and uncertain significance (n=7). Based on the evidence outlined above, the variant was classified as likely benign. -
The Val1034Met variant in TTN has been reported in 1 individual with limb girdle muscular dystrophy (Vasli 2012). This variant has also been identified by our l aboratory in 2 individuals (1 adult & 1 infant) with DCM and 1 infant with HCM, but is also present in 0.1% (10/8600) of European American chromosomes by the NH LBI Exome Sequencing Project (http://evs.gs.washington.edu/EVS/; dbSNP rs1429515 05). The population frequency of this variant raises the possibility that it is benign, but is too low to confidently rule out a disease causing role. The varia nt is located in the last base of the exon, which is part of the 5? splice regio n, and computational tools suggest an impact to splicing; however, this informat ion is not predictive enough to determine pathogenicity (their accuracy is unkno wn). In summary, the clinical significance of the Val1034Met variant is uncertai n. -
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Primary dilated cardiomyopathy Uncertain:3
This TTN truncating variant (TTNtv) was identified in one individual in this cohort and is located in an exon that is highly expressed in the heart. In the seven cohorts assessed, TTNtv were found in 14% of ambulant DCM, 22% end-stage or familial DCM, and 2% controls. Heterozygous nonsense, frameshift and canonical splice-disrupting variants found in constitutive and other highly utilised exons are highly likely to be pathogenic when identified in individuals with phenotypically confirmed DCM. TTNtv found incidentally in healthy individuals (excluding familial assessment of DCM relatives) are thought to have low penetrance, particularly when identified in exons that are not constitutively expressed in the heart. -
This TTN truncating variant (TTNtv) was identified in three individuals in this cohort and is located in an exon that is highly expressed in the heart. In the seven cohorts assessed, TTNtv were found in 14% of ambulant DCM, 22% end-stage or familial DCM, and 2% controls. Heterozygous nonsense, frameshift and canonical splice-disrupting variants found in constitutive and other highly utilised exons are highly likely to be pathogenic when identified in individuals with phenotypically confirmed DCM. TTNtv found incidentally in healthy individuals (excluding familial assessment of DCM relatives) are thought to have low penetrance, particularly when identified in exons that are not constitutively expressed in the heart. -
This TTN truncating variant (TTNtv) was identified in one individual in this cohort and is located in an exon that is highly expressed in the heart. In the seven cohorts assessed, TTNtv were found in 14% of ambulant DCM, 22% end-stage or familial DCM, and 2% controls. Heterozygous nonsense, frameshift and canonical splice-disrupting variants found in constitutive and other highly utilised exons are highly likely to be pathogenic when identified in individuals with phenotypically confirmed DCM. TTNtv found incidentally in healthy individuals (excluding familial assessment of DCM relatives) are thought to have low penetrance, particularly when identified in exons that are not constitutively expressed in the heart. -
not provided Uncertain:1Benign:2
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TTN: BP1, BP4 -
Dilated cardiomyopathy 1G Uncertain:1Benign:1
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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). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -
Tip-toe gait Pathogenic:1
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. -
Limb-girdle muscular dystrophy, recessive Uncertain:1
Vasli et al. (2012) reported the c.3100G>A (p.Val1034Met) variant in a compound heterozygous state in one patient with limb-girdle muscular dystrophy. Control data are unavailable for this variant, which is reported at a frequency of 0.002137 in the European (Finnish) population of the Exome Aggregation Consortium. The evidence for this variant is limited to a single patient. The p.Val1034Met variant is therefore classified as a variant of unknown significance but suspicious for pathogenicity for limb-girdle muscular dystrophy. -
Early-onset myopathy with fatal cardiomyopathy Uncertain:1
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 Benign:1
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
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Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1
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Myopathy, myofibrillar, 9, with early respiratory failure Benign:1
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 was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -
Tibial muscular dystrophy Benign:1
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 was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -
Cardiovascular phenotype Benign:1
Other strong data supporting benign classification -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at