rs16866469

chr2-178722052-A-G

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.22611T>C(p.His7537=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00308 in 1,612,980 control chromosomes in the GnomAD database, including 134 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.016 (70 hom., cov: 33)
  • Exomes 𝑓: 0.0017 (64 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:22
• Conservation: PhyloP100: -0.779

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=-0.58).
• BP6: Variant 2-178722052-A-G is Benign according to our data. Variant chr2-178722052-A-G is described in ClinVar as [Likely_benign]. Clinvar id is 46702.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178722052-A-G is described in Lovd as [Benign]. Variant chr2-178722052-A-G is described in Lovd as [Likely_benign].
• BP7: Synonymous conserved (PhyloP=-0.779 with no splicing effect.
• BA1: GnomAd4 highest subpopulation (AFR) allele frequency at 95% confidence interval = 0.0556 is higher than 0.05.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.22611T>C	p.His7537=	synonymous_variant	78/363	ENST00000589042.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.22611T>C	p.His7537=	synonymous_variant	78/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.503-12452A>G		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.0163 AC: 2488 AN: 152194 Hom.: 70 Cov.: 33

Gnomad AFR AF: 0.0574

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00373

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000827

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00633

Gnomad NFE AF: 0.000206

Gnomad OTH AF: 0.0158

GnomAD3 exomes AF: 0.00400 AC: 993 AN: 247976 Hom.: 24 AF XY: 0.00310 AC XY: 417 AN XY: 134506

Gnomad AFR exome AF: 0.0560

Gnomad AMR exome AF: 0.00247

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000395

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000160

Gnomad OTH exome AF: 0.00217

GnomAD4 exome AF: 0.00169 AC: 2474 AN: 1460668 Hom.: 64 Cov.: 32 AF XY: 0.00144 AC XY: 1048 AN XY: 726558

Gnomad4 AFR exome AF: 0.0608

Gnomad4 AMR exome AF: 0.00273

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000384

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000360

Gnomad4 OTH exome AF: 0.00376

GnomAD4 genome AF: 0.0164 AC: 2501 AN: 152312 Hom.: 70 Cov.: 33 AF XY: 0.0157 AC XY: 1167 AN XY: 74480

Gnomad4 AFR AF: 0.0575

Gnomad4 AMR AF: 0.00373

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00103

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000206

Gnomad4 OTH AF: 0.0156

Alfa AF: 0.00843 Hom.: 27

Bravo AF: 0.0190

Asia WGS AF: 0.00404 AC: 14 AN: 3476

EpiCase AF: 0.000109

EpiControl AF: 0.000178

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:22

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:7

Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	May 10, 2020	- -
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	GeneDx	Jan 02, 2014	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	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Dec 09, 2011	- -
Likely benign, no assertion criteria provided	clinical testing	Genetic Services Laboratory, University of Chicago	-	Likely benign based on allele frequency in 1000 Genomes Project or ESP global frequency and its presence in a patient with a rare or unrelated disease phenotype. NOT Sanger confirmed. -

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 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. -

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 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. -

not provided Benign:2

Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Sep 28, 2023	- -

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 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. -

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	- -

TTN-related disorder Benign:1

Benign, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Mar 12, 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;C1858763:Dilated cardiomyopathy 1G Benign:1

Benign, criteria provided, single submitter

clinical testing

Invitae

Feb 01, 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

Apr 01, 2016

- -

Cardiovascular phenotype Benign:1

Benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 05, 2012

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	-0.58
Cadd	Benign	0.18
Dann	Benign	0.47

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs16866469; hg19: chr2-179586779;