2-178722822-T-A

Position:

• chr2-178722822-T-A

Variant summary

Our verdict is Benign. Variant got -16 ACMG points: 0P and 16B. BP6_Very_Strong BS1 BS2

The NM_001267550.2(TTN):​c.22077A>T​(p.Gly7359Gly) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000849 in 1,613,328 control chromosomes in the GnomAD database, including 22 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00049 (2 hom., cov: 33)
  • Exomes 𝑓: 0.00089 (20 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:20
• Conservation: PhyloP100: 1.25

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:):

ACMG classification

Verdict is Benign. Variant got -16 ACMG points.

• BP6: Variant 2-178722822-T-A is Benign according to our data. Variant chr2-178722822-T-A is described in ClinVar as [Likely_benign]. Clinvar id is 46694.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178722822-T-A is described in Lovd as [Benign]. Variant chr2-178722822-T-A is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.000493 (75/152198) while in subpopulation SAS AF= 0.0139 (67/4822). AF 95% confidence interval is 0.0112. There are 2 homozygotes in gnomad4. There are 54 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd4 at 2 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2	c.22077A>T	p.Gly7359Gly	synonymous_variant	76/363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.22077A>T	p.Gly7359Gly	synonymous_variant	76/363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.000500 AC: 76 AN: 152080 Hom.: 2 Cov.: 33

Gnomad AFR AF: 0.0000483

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.0141

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000883

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00176 AC: 436 AN: 248372 Hom.: 6 AF XY: 0.00245 AC XY: 330 AN XY: 134734

Gnomad AFR exome AF: 0.0000646

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0140

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000534

Gnomad OTH exome AF: 0.000333

GnomAD4 exome AF: 0.000886 AC: 1294 AN: 1461130 Hom.: 20 Cov.: 34 AF XY: 0.00126 AC XY: 913 AN XY: 726814

Gnomad4 AFR exome AF: 0.0000598

Gnomad4 AMR exome AF: 0.0000448

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0137

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000531

Gnomad4 OTH exome AF: 0.000779

GnomAD4 genome AF: 0.000493 AC: 75 AN: 152198 Hom.: 2 Cov.: 33 AF XY: 0.000726 AC XY: 54 AN XY: 74398

Gnomad4 AFR AF: 0.0000481

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.0139

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000883

Gnomad4 OTH AF: 0.00

Bravo AF: 0.000174

Asia WGS AF: 0.00376 AC: 13 AN: 3476

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:20

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:7

Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Sep 25, 2019	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Apr 17, 2017	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. -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Oct 06, 2015	- -
Likely benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Apr 04, 2015	- -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Nov 20, 2014	p.Gly6115Gly in exon 73 of TTN: This variant is not expected to have clinical si gnificance because it has been identified in 1.5% (241/16480) of South Asian chr omosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.o rg). -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 19, 2023	- -

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

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Early-onset myopathy with fatal cardiomyopathy Benign:2

Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

not provided Benign:2

Benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Apr 01, 2023	TTN: BS1, BS2 -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -

Tibial muscular dystrophy Benign:2

Benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 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. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

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

Benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 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. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

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

Jan 04, 2024

- -

Dilated cardiomyopathy 1G Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Cardiomyopathy Benign:1

Benign, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Nov 02, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.60
CADD	Benign	8.9
DANN	Benign	0.64

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.21		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.21		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs202102237; hg19: chr2-179587549; COSMIC: COSV105217427; COSMIC: COSV105217427;