Our verdict is Benign. Variant got -12 ACMG points: 1P and 13B. PP2BP4_StrongBP6BS1BS2
The NM_001267550.2(TTN):c.78068T>C(p.Ile26023Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000237 in 1,613,368 control chromosomes in the GnomAD database, including 5 homozygotes. In-silico tool predicts a benign outcome for this variant. 12/18 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
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]
PP2 - Missense variant in a gene that has a low rate of benign missense variation and in which missense variants are a common mechanism of disease
Missense variant where missense usually causes diseases, TTN
BP4
?
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 (MetaRNN=0.008518577).
BP6
?
BP6 - Reputable source recently reports variant as benign, but the evidence is not available to the laboratory to perform an independent evaluation
Variant 2-178568064-A-G is Benign according to our data. Variant chr2-178568064-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 283480.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=6, Uncertain_significance=1, Benign=1}. Variant chr2-178568064-A-G is described in Lovd as [Likely_benign].
BS1
?
BS1 - Allele frequency is greater than expected for disorder
Variant frequency is greater than expected in population sas. gnomad4_exome allele frequency = 0.000247 (361/1461178) while in subpopulation SAS AF= 0.00393 (339/86244). AF 95% confidence interval is 0.00359. There are 5 homozygotes in gnomad4_exome. There are 261 alleles in male gnomad4_exome subpopulation. Median coverage is 41. This position pass quality control queck.
BS2
?
BS2 - Observed in a healthy adult individual for a recessive (homozygous), dominant (heterozygous), or X-linked (hemizygous) disorder, with full penetrance expected at an early age
Likely benign, criteria provided, single submitter
clinical testing
Women's Health and Genetics/Laboratory Corporation of America, LabCorp
Apr 04, 2022
- -
Likely benign, criteria provided, single submitter
clinical testing
Eurofins Ntd Llc (ga)
Sep 23, 2015
- -
Cardiomyopathy Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario
Oct 27, 2016
- -
TTN-related disorder Benign:1
Likely benign, criteria provided, single submitter
clinical testing
PreventionGenetics, part of Exact Sciences
Jan 31, 2022
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). -
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1
Likely benign, criteria provided, single submitter
clinical testing
Invitae
Dec 06, 2023
- -
not provided Benign:1
Benign, criteria provided, single submitter
clinical testing
GeneDx
Mar 25, 2020
- -
Hypertrophic cardiomyopathy Benign:1
Likely benign, criteria provided, single submitter
research
Genetics and Genomics Program, Sidra Medicine
-
- -
Cardiovascular phenotype Benign:1
Likely benign, criteria provided, single submitter
clinical testing
Ambry Genetics
Sep 12, 2018
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. -