2-178729493-T-G

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.18663A>C(p.Glu6221Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000112 in 1,613,638 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. E6221G) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00011 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00011 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5B:2

Conservation

PhyloP100: 0.814

Publications

2 publications found

Variant links:

COSMIC-nc: COSV60390876

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=0.055708796).

BP6

Variant 2-178729493-T-G is Benign according to our data. Variant chr2-178729493-T-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 46642.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.18663A>C	p.Glu6221Asp	missense_variant	Exon 64 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.18663A>C	p.Glu6221Asp	missense_variant	Exon 64 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes

AF:

0.000105

AC:

AN:

152146

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

Gnomad ASJ

AF:

0.00260

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000588

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000926

AC:

AN:

248470

AF XY:

0.0000965

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00110

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000712

Gnomad OTH exome

AF:

0.000332

GnomAD4 exome

AF:

0.000112

AC:

164

AN:

1461374

Hom.:

Cov.:

AF XY:

0.000114

AC XY:

AN XY:

726970

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33450

American (AMR)

AF:

0.0000671

AC:

AN:

44700

Ashkenazi Jewish (ASJ)

AF:

0.00153

AC:

AN:

26120

East Asian (EAS)

AF:

0.00

AC:

AN:

39682

South Asian (SAS)

AF:

0.0000348

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53398

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5760

European-Non Finnish (NFE)

AF:

0.0000936

AC:

104

AN:

1111650

Other (OTH)

AF:

0.000232

AC:

AN:

60360

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.502

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:

0.000105

AC:

AN:

152264

Hom.:

Cov.:

AF XY:

0.0000940

AC XY:

AN XY:

74456

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41566

American (AMR)

AF:

0.0000654

AC:

AN:

15288

Ashkenazi Jewish (ASJ)

AF:

0.00260

AC:

AN:

3464

East Asian (EAS)

AF:

0.00

AC:

AN:

5176

South Asian (SAS)

AF:

0.000207

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000588

AC:

AN:

67996

Other (OTH)

AF:

0.00

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

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:

0.000214

Hom.:

Bravo

AF:

0.000106

TwinsUK

AF:

0.000539

AC:

ALSPAC

AF:

0.00

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000243

AC:

ExAC

AF:

0.0000993

AC:

EpiCase

AF:

0.000164

EpiControl

AF:

0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:5Benign:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:3Benign:1

Jul 11, 2019

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is associated with the following publications: (PMID: 24503780)

Jul 28, 2015

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Mar 01, 2019

CeGaT Center for Human Genetics Tuebingen

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Jun 12, 2024

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The TTN c.18663A>C; p.Glu6221Asp variant (rs369544339; ClinVar Variation ID: 46642) is rare in the general population (<0.2% allele frequency in the Genome Aggregation Database) and has not been reported in the medical literature in association with dilated cardiomyopathy (DCM) or other TTN-related disease. The clinical relevance of rare missense variants in this gene, which are identified on average once per individual sequenced in affected populations (Herman 2012), is not well understood. Yet, evidence suggests that the vast majority of such missense variants do not contribute to the clinical outcome of DCM (Begay 2015). Thus, the clinical significance of the p.Glu6221Asp variant cannot be determined with certainty. References: Begay RL et al. Role of Titin Missense Variants in Dilated Cardiomyopathy. J Am Heart Assoc. 2015 Nov 13;4(11). PMID: 26567375. Herman DS et al. Truncations of titin causing dilated cardiomyopathy. N Engl J Med. 2012 Feb 16;366(7):619-28. PMID: 22335739. Linke WA and Hamdani N. Gigantic business: titin properties and function through thick and thin. Circ Res 2014; 114(6): 1052-1068. PMID: 24625729.

not specified

Uncertain:1Benign:1

Sep 27, 2019

Athena Diagnostics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Feb 20, 2015

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.Glu4977Asp variant in TTN has been previously identified by our laboratory in 1 Caucasian child with DCM and 1 Caucasian adult with ARVC. This variant has also been identified in 11/67530 European chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs369544339). Computatio nal prediction tools and conservation analysis suggest the p.Glu4977Asp variant may not impact the protein, though this information is not predictive enough to rule out pathogenicity. In summary, the clinical significance of the p.Glu4977As p variant is uncertain.

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

Uncertain:1

Dec 20, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.42

BayesDel_addAF

Benign

-0.24

BayesDel_noAF

Benign

-0.40

CADD

Benign

(source)

DANN

Benign

0.81

DEOGEN2

Benign

0.0

.;.;.;.

Eigen

Benign

0.10

Eigen_PC

Benign

0.089

FATHMM_MKL

Uncertain

0.87

LIST_S2

Benign

0.71

T;T;.;T

M_CAP

Benign

0.033

MetaRNN

Benign

0.056

T;T;T;T

MetaSVM

Benign

-0.69

MutationAssessor

Benign

0.0

.;.;.;.

PhyloP100

0.81

PrimateAI

Uncertain

0.53

PROVEAN

Benign

-1.9

N;.;.;.

REVEL

Benign

0.15

Sift

Benign

0.34

T;.;.;.

Sift4G

Pathogenic

0.0

.;.;.;.

Vest4

0.33

ClinPred

0.090

GERP RS

2.2

Mutation Taster

=57/43

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

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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