2-178583121-T-C

Position:

• chr2-178583121-T-C

Variant summary

Our verdict is Benign. Variant got -21 ACMG points: 0P and 21B. BP4_Strong BP6_Very_Strong BP7 BA1

The NM_001267550.2(TTN):​c.65682A>G​(p.Thr21894=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.279 in 1,610,804 control chromosomes in the GnomAD database, including 75,624 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★★). Synonymous variant affecting the same amino acid position (i.e. T21894T) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.37 (12056 hom., cov: 32)
  • Exomes 𝑓: 0.27 (63568 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Benign criteria provided, multiple submitters, no conflicts B:21
• Conservation: PhyloP100: -1.66

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]

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]

ACMG classification

Verdict is Benign. Variant got -21 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.77).
• BP6: Variant 2-178583121-T-C is Benign according to our data. Variant chr2-178583121-T-C is described in ClinVar as [Benign]. Clinvar id is 47227.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178583121-T-C is described in Lovd as [Benign].
• BP7: Synonymous conserved (PhyloP=-1.65 with no splicing effect.
• BA1: GnomAd4 highest subpopulation (EAS) allele frequency at 95% confidence interval = 0.683 is higher than 0.05.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.65682A>G	p.Thr21894=	synonymous_variant	313/363	ENST00000589042.5
TTN-AS1	NR_038272.1	n.2309T>C		non_coding_transcript_exon_variant	9/17

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.65682A>G	p.Thr21894=	synonymous_variant	313/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.417-14475T>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.365 AC: 55341 AN: 151786 Hom.: 12006 Cov.: 32

Gnomad AFR AF: 0.547

Gnomad AMI AF: 0.561

Gnomad AMR AF: 0.388

Gnomad ASJ AF: 0.293

Gnomad EAS AF: 0.702

Gnomad SAS AF: 0.523

Gnomad FIN AF: 0.285

Gnomad MID AF: 0.282

Gnomad NFE AF: 0.227

Gnomad OTH AF: 0.330

GnomAD3 exomes AF: 0.355 AC: 87026 AN: 245224 Hom.: 18486 AF XY: 0.352 AC XY: 46834 AN XY: 133036

Gnomad AFR exome AF: 0.549

Gnomad AMR exome AF: 0.432

Gnomad ASJ exome AF: 0.289

Gnomad EAS exome AF: 0.705

Gnomad SAS exome AF: 0.521

Gnomad FIN exome AF: 0.278

Gnomad NFE exome AF: 0.227

Gnomad OTH exome AF: 0.309

GnomAD4 exome AF: 0.270 AC: 393832 AN: 1458900 Hom.: 63568 Cov.: 34 AF XY: 0.275 AC XY: 199675 AN XY: 725586

Gnomad4 AFR exome AF: 0.560

Gnomad4 AMR exome AF: 0.431

Gnomad4 ASJ exome AF: 0.289

Gnomad4 EAS exome AF: 0.695

Gnomad4 SAS exome AF: 0.510

Gnomad4 FIN exome AF: 0.278

Gnomad4 NFE exome AF: 0.218

Gnomad4 OTH exome AF: 0.306

GnomAD4 genome AF: 0.365 AC: 55452 AN: 151904 Hom.: 12056 Cov.: 32 AF XY: 0.375 AC XY: 27837 AN XY: 74228

Gnomad4 AFR AF: 0.548

Gnomad4 AMR AF: 0.388

Gnomad4 ASJ AF: 0.293

Gnomad4 EAS AF: 0.702

Gnomad4 SAS AF: 0.521

Gnomad4 FIN AF: 0.285

Gnomad4 NFE AF: 0.227

Gnomad4 OTH AF: 0.338

Alfa AF: 0.263 Hom.: 7734

Bravo AF: 0.379

Asia WGS AF: 0.620 AC: 2151 AN: 3474

ClinVar

Significance: Benign

Submissions summary: Benign:21

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:8

Benign, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	-	- -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
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	Genetic Services Laboratory, University of Chicago	Aug 15, 2013	- -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 19, 2019	- -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Sep 27, 2011	- -
Benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	May 29, 2013	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Oct 31, 2012	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. -

Autosomal recessive limb-girdle muscular dystrophy type 2J Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
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. -

Early-onset myopathy with fatal cardiomyopathy Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
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. -

not provided Benign:2

Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Nov 02, 2018	- -
Benign, criteria provided, single submitter	not provided	Breakthrough Genomics, Breakthrough Genomics	-	- -

Tibial muscular dystrophy Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
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. -

Myopathy, myofibrillar, 9, with early respiratory failure Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
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. -

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

Feb 01, 2024

- -

Dilated cardiomyopathy 1G 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. -

Cardiovascular phenotype Benign:1

Benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 16, 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: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.77
CADD	Benign	0.026
DANN	Benign	0.63

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs4894029; hg19: chr2-179447848; COSMIC: COSV60287562; COSMIC: COSV60287562;