Our verdict is Benign. Variant got -20 ACMG points: 0P and 20B. BP4_StrongBP6_Very_StrongBA1
The NM_001267550.2(TTN):c.40141+7G>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00269 in 1,549,284 control chromosomes in the GnomAD database, including 98 homozygotes. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Benign (★★).
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]
TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]
BP4 - Multiple lines of computational evidence suggest no impact on gene or gene product (conservation, evolutionary, splicing impact, etc.)
Computational evidence support a benign effect (BayesDel_noAF=-0.83).
BP6
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BP6 - Reputable source recently reports variant as benign, but the evidence is not available to the laboratory to perform an independent evaluation
Variant 2-178647374-C-T is Benign according to our data. Variant chr2-178647374-C-T is described in ClinVar as [Benign]. Clinvar id is 413055.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178647374-C-T is described in Lovd as [Benign]. Variant chr2-178647374-C-T is described in Lovd as [Likely_benign].
BA1
?
BA1 - Allele frequency is >5% in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium
GnomAdExome4 highest subpopulation (AFR) allele frequency at 95% confidence interval = 0.051 is higher than 0.05.
ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories
Sep 06, 2023
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Likely benign, no assertion criteria provided
clinical testing
Genome Diagnostics Laboratory, University Medical Center Utrecht
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Likely benign, no assertion criteria provided
clinical testing
Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)
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not specified Benign:2
Benign, no assertion criteria provided
clinical testing
Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center
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Benign, no assertion criteria provided
clinical testing
Clinical Genetics, Academic Medical Center
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TTN-related disorder Benign:1
Benign, criteria provided, single submitter
clinical testing
PreventionGenetics, part of Exact Sciences
May 20, 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 Benign:1
Benign, criteria provided, single submitter
clinical testing
Genome-Nilou Lab
Sep 10, 2021
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Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1
Benign, criteria provided, single submitter
clinical testing
Invitae
Jan 31, 2024
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Early-onset myopathy with fatal cardiomyopathy Benign:1
Benign, criteria provided, single submitter
clinical testing
Genome-Nilou Lab
Sep 10, 2021
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Tibial muscular dystrophy Benign:1
Benign, criteria provided, single submitter
clinical testing
Genome-Nilou Lab
Sep 10, 2021
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Myopathy, myofibrillar, 9, with early respiratory failure Benign:1