2-178566813-C-T

Variant names:

Variant summary

Our verdict is Benign. The variant received -13 ACMG points: 0P and 13B. BP4_StrongBP6BS1BS2

The NM_001267550.2(TTN):c.79319G>A(p.Arg26440His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00105 in 1,613,268 control chromosomes in the GnomAD database, including 20 homozygotes. In-silico tool predicts a benign outcome for this variant. 14/19 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. R26440C) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0051 ( 7 hom., cov: 33)

Exomes 𝑓: 0.00063 ( 13 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1B:20

Conservation

PhyloP100: 2.66

Publications

8 publications found

Variant links:

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 links:

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]

TTN-AS1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -13 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.005654186).

BP6

Variant 2-178566813-C-T is Benign according to our data. Variant chr2-178566813-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 47375.

BS1

Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00507 (771/152154) while in subpopulation AFR AF = 0.0167 (695/41536). AF 95% confidence interval is 0.0157. There are 7 homozygotes in GnomAd4. There are 395 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.

BS2

High Homozygotes in GnomAd4 at 7 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.79319G>A	p.Arg26440His	missense_variant	Exon 326 of 363	ENST00000589042.5	NP_001254479.2	A0A0A0MTS7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.79319G>A	p.Arg26440His	missense_variant	Exon 326 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.00503

AC:

764

AN:

152036

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0166

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00269

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00104

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00949

Gnomad NFE

AF:

0.000221

Gnomad OTH

AF:

0.00573

GnomAD2 exomes

AF:

0.00133

AC:

331

AN:

248036

AF XY:

0.00108

show subpopulations

Gnomad AFR exome

AF:

0.0147

Gnomad AMR exome

AF:

0.00154

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000470

Gnomad NFE exome

AF:

0.000196

Gnomad OTH exome

AF:

0.00183

GnomAD4 exome

AF:

0.000632

AC:

923

AN:

1461114

Hom.:

Cov.:

AF XY:

0.000576

AC XY:

419

AN XY:

726860

show subpopulations

African (AFR)

AF:

0.0169

AC:

565

AN:

33450

American (AMR)

AF:

0.00188

AC:

AN:

44700

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26126

East Asian (EAS)

AF:

0.0000505

AC:

AN:

39640

South Asian (SAS)

AF:

0.000626

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.0000565

AC:

AN:

53142

Middle Eastern (MID)

AF:

0.00225

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.0000855

AC:

AN:

1111688

Other (OTH)

AF:

0.00177

AC:

107

AN:

60348

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.474

Heterozygous variant carriers

133

200

266

333

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

110

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00507

AC:

771

AN:

152154

Hom.:

Cov.:

AF XY:

0.00531

AC XY:

395

AN XY:

74370

show subpopulations

African (AFR)

AF:

0.0167

AC:

695

AN:

41536

American (AMR)

AF:

0.00269

AC:

AN:

15258

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5154

South Asian (SAS)

AF:

0.00104

AC:

AN:

4820

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10614

Middle Eastern (MID)

AF:

0.0102

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000221

AC:

AN:

67984

Other (OTH)

AF:

0.00567

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.498

Heterozygous variant carriers

127

169

211

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Genome Hom

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00179

Hom.:

Bravo

AF:

0.00597

ESP6500AA

AF:

0.0174

AC:

ESP6500EA

AF:

0.000243

AC:

ExAC

AF:

0.00155

AC:

187

Asia WGS

AF:

0.00144

AC:

AN:

3478

EpiCase

AF:

0.000218

EpiControl

AF:

0.000296

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1Benign:20

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Benign:9

May 01, 2014

GeneDx

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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. -

Mar 02, 2012

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Arg23872His in exon 275 of TTN: This variant is not expected to have clinical si gnificance because it has been identified in 1.6% (48/3030) of African American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http: //evs.gs.washington.edu/EVS; dbSNP rs56044609). -

Genetic Services Laboratory, University of Chicago

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

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. -

Apr 21, 2017

Athena Diagnostics

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Clinical Genetics, Academic Medical Center

Significance:Benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Apr 09, 2025

Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance:Benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Oct 30, 2019

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: TTN c.71615G>A (p.Arg23872His) results in a non-conservative amino acid change located in the A-band domain of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.0013 in 248036 control chromosomes, predominantly at a frequency of 0.015 within the African or African-American subpopulation in the gnomAD database, including 1 homozygotes. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 24 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Cardiomyopathy phenotype (0.00063), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African or African-American origin. To our knowledge, no occurrence of c.71615G>A in individuals affected with Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as benign. Based on the evidence outlined above, the variant was classified as benign. -

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:research

- -

Cardiomyopathy

Benign:2

Oct 17, 2017

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

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jan 24, 2019

Center for Advanced Laboratory Medicine, UC San Diego Health, University of California San Diego

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Benign:2

Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Jun 21, 2024

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Benign:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases allowed determination this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

TTN-related disorder

Benign:1

May 29, 2019

PreventionGenetics, part of Exact Sciences

Significance:Benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

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

Feb 02, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Dilated cardiomyopathy 1G

Benign:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Tibial muscular dystrophy

Benign:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Cardiovascular phenotype

Benign:1

Jul 19, 2013

Ambry Genetics

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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

AlphaMissense

Benign

0.12

BayesDel_addAF

Benign

-0.39

BayesDel_noAF

Benign

-0.32

CADD

Benign

(source)

DANN

Benign

0.88

Eigen

Benign

-0.056

Eigen_PC

Benign

0.084

FATHMM_MKL

Uncertain

0.94

LIST_S2

Uncertain

0.89

D;D;D;.;D;D;D

MetaRNN

Benign

0.0057

T;T;T;T;T;T;T

MetaSVM

Benign

-0.94

MutationAssessor

Benign

1.7

.;.;.;L;.;.;L

PhyloP100

2.7

PrimateAI

Uncertain

0.64

PROVEAN

Uncertain

-3.3

D;D;.;.;D;D;.

REVEL

Benign

0.10

Sift

Benign

0.052

T;T;.;.;T;T;.

Polyphen

0.096

.;.;.;B;.;.;B

Vest4

0.45

MVP

0.14

MPC

0.11

ClinPred

0.019

GERP RS

4.0

Mutation Taster

=96/4

polymorphism

(source)

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

You must be logged in to view publications. This limit was set because tens of millions (!) of queries from AI bots are generated daily.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over