2-178557743-G-C

Variant names:

Variant summary

Our verdict is Benign. The variant received -9 ACMG points: 0P and 9B. BP4_StrongBP6BS1

The NM_001267550.2(TTN):c.87611C>G(p.Thr29204Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000106 in 1,613,948 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. T29204T) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.00051 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000064 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:6

Conservation

PhyloP100: 2.72

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:

ENSG00000279598 (HGNC:):

ENSG00000279598 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -9 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.010675371).

BP6

Variant 2-178557743-G-C is Benign according to our data. Variant chr2-178557743-G-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 202942.

BS1

Variant frequency is greater than expected in population afr. GnomAdExome4 allele frequency = 0.0000643 (94/1461640) while in subpopulation AFR AF = 0.00248 (83/33480). AF 95% confidence interval is 0.00205. There are 0 homozygotes in GnomAdExome4. There are 39 alleles in the male GnomAdExome4 subpopulation. Median coverage is 33. This position passed quality control check.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTN	NM_001267550.2	MANE Select	c.87611C>G	p.Thr29204Arg	missense	Exon 328 of 363	NP_001254479.2
TTN	NM_001256850.1		c.82688C>G	p.Thr27563Arg	missense	Exon 278 of 313	NP_001243779.1
TTN	NM_133378.4		c.79907C>G	p.Thr26636Arg	missense	Exon 277 of 312	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.87611C>G	p.Thr29204Arg	missense	Exon 328 of 363	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.87455C>G	p.Thr29152Arg	missense	Exon 326 of 361	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.87335C>G	p.Thr29112Arg	missense	Exon 326 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.000513

AC:

AN:

152190

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00179

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000196

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:

0.00

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.000157

AC:

AN:

248992

AF XY:

0.000155

show subpopulations

Gnomad AFR exome

AF:

0.00245

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000643

AC:

AN:

1461640

Hom.:

Cov.:

AF XY:

0.0000536

AC XY:

AN XY:

727102

show subpopulations

African (AFR)

AF:

0.00248

AC:

AN:

33480

American (AMR)

AF:

0.0000671

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53400

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111826

Other (OTH)

AF:

0.000133

AC:

AN:

60370

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.486

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:

0.000506

AC:

AN:

152308

Hom.:

Cov.:

AF XY:

0.000537

AC XY:

AN XY:

74482

show subpopulations

African (AFR)

AF:

0.00176

AC:

AN:

41574

American (AMR)

AF:

0.000196

AC:

AN:

15302

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5178

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10606

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68032

Other (OTH)

AF:

0.000473

AC:

AN:

2112

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.506

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:

0.0000450

Hom.:

Bravo

AF:

0.000620

ESP6500AA

AF:

0.00128

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.000215

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:6

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:1Benign:3

Apr 11, 2023

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

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: TTN c.79907C>G (p.Thr26636Arg) results in a non-conservative amino acid change located in the A-band region (cardiodb.org) 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 0.00016 in 248992 control chromosomes, predominantly at a frequency of 0.0025 within the African or African-American subpopulation in the gnomAD database. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 6 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Dilated Cardiomyopathy phenotype (0.00039), 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.79907C>G in individuals affected with Dilated Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as VUS and likely benign. Based on the evidence outlined above, the variant was classified as likely benign.

Aug 14, 2016

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant classified as Uncertain Significance - Favor Benign. The p.Thr26636Arg v ariant in TTN has not been previously reported in individuals with cardiomyopath y, but has been identified in 0.3% (25/9802) of African chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs72648228) . Computational prediction tools and conservation analysis do not provide strong support for or against an impact to the protein. In summary, while the clinical significance of the p.Thr26636Arg variant is uncertain, its frequency suggests that it is more likely to be benign.

Dec 28, 2017

GeneDx

Significance:Likely 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.

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

not provided

Uncertain:1

May 25, 2018

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

TTN-related disorder

Benign:1

Sep 25, 2024

PreventionGenetics, part of Exact Sciences

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

This variant is classified as likely 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

Jan 28, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Cardiovascular phenotype

Benign:1

May 14, 2018

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: seen in unaffected individuals, 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 v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.093

BayesDel_addAF

Benign

-0.33

BayesDel_noAF

Benign

-0.25

CADD

Benign

(source)

DANN

Benign

0.89

Eigen

Uncertain

0.20

Eigen_PC

Uncertain

0.26

FATHMM_MKL

Uncertain

0.84

LIST_S2

Benign

0.85

M_CAP

Benign

0.029

MetaRNN

Benign

0.011

MetaSVM

Benign

-0.81

MutationAssessor

Benign

1.7

PhyloP100

2.7

PrimateAI

Uncertain

0.63

PROVEAN

Uncertain

-3.5

REVEL

Benign

0.10

Sift

Benign

0.26

Polyphen

0.76

Vest4

0.47

MVP

0.31

MPC

0.19

ClinPred

0.098

GERP RS

3.8

Mutation Taster

=65/35

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over