Our verdict is Likely benign. Variant got -4 ACMG points: 1P and 5B. PP2BP4_StrongBP6
The NM_001267550.2(TTN):c.103913G>A(p.Arg34638His) variant causes a missense change. The variant allele was found at a frequency of 0.0000818 in 1,613,894 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R34638C) has been classified as Likely 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]
Verdict is Likely_benign. Variant got -4 ACMG points.
PP2
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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
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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=0.021734595).
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 2-178532702-C-T is Benign according to our data. Variant chr2-178532702-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 229569.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Benign=2, Uncertain_significance=4}.
Uncertain significance, criteria provided, single submitter
clinical testing
Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine
Jun 25, 2015
Variant classified as Uncertain Significance - Favor Benign. The p.Arg32070His v ariant in TTN has not been previously reported in individuals with cardiomyopath y, but has been identified in 0.1% (18/16510) of South Asian chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs3715 28685). One mammal (pika) carries a histidine (His) at this position, raising th e possibility that this change may be tolerated. Additional computational predic tion tools do not provide strong support for or against an impact to the protein . In summary, while the clinical significance of the p.Arg32070His variant is un certain, its frequency and lack of conservation suggests that it is more likely to be benign. -
Autosomal recessive limb-girdle muscular dystrophy type 2J Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Illumina Laboratory Services, Illumina
Jan 13, 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 13, 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 13, 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. -
not provided Benign:1
Likely benign, criteria provided, single submitter
clinical testing
GeneDx
Sep 27, 2019
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Myopathy, myofibrillar, 9, with early respiratory failure Benign:1
Benign, criteria provided, single submitter
clinical testing
Illumina Laboratory Services, Illumina
Jan 13, 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 13, 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. -