2-178784339-C-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4BP6

The NM_001267550.2(TTN):c.2506G>A(p.Gly836Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000039 in 1,613,886 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts 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. G836C) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000046 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000038 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4B:1

Conservation

PhyloP100: 7.51

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 Gene-Disease associations (from GenCC):

dilated cardiomyopathy
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
dilated cardiomyopathy 1G
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
early-onset myopathy with fatal cardiomyopathy
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, G2P
TTN-related myopathy
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
myopathy, myofibrillar, 9, with early respiratory failure
Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, ClinGen, Ambry Genetics
tibial muscular dystrophy
Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen, Orphanet
autosomal recessive limb-girdle muscular dystrophy type 2J
Inheritance: AR Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
hypertrophic cardiomyopathy 9
Inheritance: AD Classification: MODERATE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), PanelApp Australia
familial isolated dilated cardiomyopathy
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
autosomal recessive centronuclear myopathy
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
arrhythmogenic right ventricular cardiomyopathy
Inheritance: AD Classification: LIMITED Submitted by: ClinGen
congenital myopathy
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
hereditary skeletal muscle disorder
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
hypertrophic cardiomyopathy
Inheritance: AD Classification: LIMITED Submitted by: ClinGen

TTN links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.2930014).

BP6

Variant 2-178784339-C-T is Benign according to our data. Variant chr2-178784339-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 597613.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.2506G>A	p.Gly836Ser	missense_variant	Exon 16 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.2506G>A	p.Gly836Ser	missense_variant	Exon 16 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes

AF:

0.0000460

AC:

AN:

152144

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000966

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000441

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000280

AC:

AN:

249958

AF XY:

0.0000370

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000109

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000267

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000383

AC:

AN:

1461742

Hom.:

Cov.:

AF XY:

0.0000399

AC XY:

AN XY:

727166

show subpopulations

African (AFR)

AF:

0.0000896

AC:

AN:

33478

American (AMR)

AF:

0.0000447

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.0000756

AC:

AN:

39670

South Asian (SAS)

AF:

0.0000464

AC:

AN:

86252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53370

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.0000396

AC:

AN:

1111960

Other (OTH)

AF:

0.00

AC:

AN:

60392

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.463

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:

0.0000460

AC:

AN:

152144

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74328

show subpopulations

African (AFR)

AF:

0.0000966

AC:

AN:

41424

American (AMR)

AF:

0.00

AC:

AN:

15266

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10618

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000441

AC:

AN:

68034

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.504

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:

0.000141

Hom.:

Bravo

AF:

0.0000189

ExAC

AF:

0.0000494

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:1Benign:1

Jun 21, 2018

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Mar 26, 2020

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not specified

Uncertain:1

Dec 20, 2024

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

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: TTN c.2506G>A (p.Gly836Ser) results in a non-conservative amino acid change located in the region near Z-disk of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 2.8e-05 in 249958 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.2506G>A has been reported in the literature in an individual with sudden unexplained death (Modena_2020). These report(s) do not provide unequivocal conclusions about association of the variant with Dilated Cardiomyopathy. Co-occurrences with other pathogenic variant(s) have been reported ( MYBPC3 c.3624delC , p.Lys1209SerfsX28), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication have been ascertained in the context of this evaluation (PMID: 32101375). ClinVar contains an entry for this variant (Variation ID: 597613). Based on the evidence outlined above, the variant was classified as uncertain significance. -

TTN-related disorder

Uncertain:1

Sep 19, 2024

PreventionGenetics, part of Exact Sciences

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

The TTN c.2506G>A variant is predicted to result in the amino acid substitution p.Gly836Ser. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.010% of alleles in individuals of East Asian descent in gnomAD. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Cardiovascular phenotype

Uncertain:1

Aug 24, 2018

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.G790S variant (also known as c.2368G>A), located in coding exon 14 of the TTN gene, results from a G to A substitution at nucleotide position 2368. The glycine at codon 790 is replaced by serine, an amino acid with similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.44

BayesDel_addAF

Benign

-0.042

BayesDel_noAF

Uncertain

-0.070

CADD

Uncertain

(source)

DANN

Uncertain

0.98

Eigen

Pathogenic

0.70

Eigen_PC

Pathogenic

0.72

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.96

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

M_CAP

Benign

0.065

MetaRNN

Benign

0.29

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

MetaSVM

Uncertain

0.23

PhyloP100

7.5

PrimateAI

Uncertain

0.69

PROVEAN

Uncertain

-3.8

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

REVEL

Uncertain

0.46

Sift

Pathogenic

0.0

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

Sift4G

Uncertain

0.012

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

Polyphen

1.0

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

Vest4

0.35

MutPred

0.32

Gain of glycosylation at G836 (P = 0.0423);.;Gain of glycosylation at G836 (P = 0.0423);Gain of glycosylation at G836 (P = 0.0423);.;.;Gain of glycosylation at G836 (P = 0.0423);Gain of glycosylation at G836 (P = 0.0423);

MVP

0.59

MPC

0.39

ClinPred

0.68

GERP RS

5.5

Mutation Taster

=69/31

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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