2-178715249-C-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4_StrongBP6

The NM_001267550.2(TTN):c.25937G>A(p.Arg8646His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000108 in 1,601,940 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/19 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. R8646C) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.00018 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00010 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3B:3

Conservation

PhyloP100: -0.321

Publications

4 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: Likely_benign. The variant received -5 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.02284503).

BP6

Variant 2-178715249-C-T is Benign according to our data. Variant chr2-178715249-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 263481.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.25937G>A	p.Arg8646His	missense_variant	Exon 90 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.25937G>A	p.Arg8646His	missense_variant	Exon 90 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes

AF:

0.000165

AC:

AN:

151866

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000387

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000736

Gnomad OTH

AF:

0.000480

GnomAD2 exomes

AF:

0.0000708

AC:

AN:

240094

AF XY:

0.0000692

show subpopulations

Gnomad AFR exome

AF:

0.000457

Gnomad AMR exome

AF:

0.0000306

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000364

Gnomad OTH exome

AF:

0.000174

GnomAD4 exome

AF:

0.000101

AC:

146

AN:

1449956

Hom.:

Cov.:

AF XY:

0.0000986

AC XY:

AN XY:

720216

show subpopulations

African (AFR)

AF:

0.000427

AC:

AN:

32796

American (AMR)

AF:

0.0000467

AC:

AN:

42836

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25646

East Asian (EAS)

AF:

0.0000253

AC:

AN:

39586

South Asian (SAS)

AF:

0.0000715

AC:

AN:

83954

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53216

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5542

European-Non Finnish (NFE)

AF:

0.000106

AC:

117

AN:

1106610

Other (OTH)

AF:

0.000100

AC:

AN:

59770

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.459

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

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

GnomAD4 genome

AF:

0.000178

AC:

AN:

151984

Hom.:

Cov.:

AF XY:

0.000135

AC XY:

AN XY:

74290

show subpopulations

African (AFR)

AF:

0.000434

AC:

AN:

41444

American (AMR)

AF:

0.000131

AC:

AN:

15272

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5168

South Asian (SAS)

AF:

0.000208

AC:

AN:

4816

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10532

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000736

AC:

AN:

67970

Other (OTH)

AF:

0.000475

AC:

AN:

2106

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.501

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

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:

0.000140

Hom.:

Bravo

AF:

0.000238

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.000259

AC:

ESP6500AA

AF:

0.000543

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000828

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.0000594

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3Benign:3

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:1Benign:1

Aug 05, 2020

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 15, 2022

Revvity Omics, Revvity

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

TTN-related disorder

Uncertain:1

Aug 21, 2024

PreventionGenetics, part of Exact Sciences

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

The TTN c.25937G>A variant is predicted to result in the amino acid substitution p.Arg8646His. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.042% of alleles in individuals of African descent in gnomAD. Although we suspect that this variant may be benign, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G

Uncertain:1

Jun 19, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not specified

Benign:1

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

- -

Cardiovascular phenotype

Benign:1

Jan 08, 2013

Ambry Genetics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This alteration is classified as likely 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

0.074

BayesDel_addAF

Benign

-0.49

BayesDel_noAF

Benign

-0.62

CADD

Benign

(source)

DANN

Benign

0.89

Eigen

Benign

-0.68

Eigen_PC

Benign

-0.59

FATHMM_MKL

Benign

0.39

LIST_S2

Benign

0.38

T;T;.;T

M_CAP

Benign

0.029

MetaRNN

Benign

0.023

T;T;T;T

MetaSVM

Benign

-1.0

PhyloP100

-0.32

PrimateAI

Benign

0.24

PROVEAN

Benign

-2.0

N;.;.;.

REVEL

Benign

0.060

Sift

Benign

0.54

T;.;.;.

Polyphen

0.0

.;.;B;B

Vest4

0.12

MVP

0.055

MPC

0.10

ClinPred

0.035

GERP RS

1.4

Mutation Taster

=84/16

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.030

Details are displayed if max score is > 0.2

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

Publications

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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