2-178592871-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.59248G>A(p.Gly19750Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000276 in 1,613,304 control chromosomes in the GnomAD database, including 1 homozygotes. 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. G19750C) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000099 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00029 ( 1 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:9B:6

Conservation

PhyloP100: 7.86

Publications

9 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 -2 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.39618886).

BP6

Variant 2-178592871-C-T is Benign according to our data. Variant chr2-178592871-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 130675.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.59248G>A	p.Gly19750Ser	missense_variant	Exon 300 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.59248G>A	p.Gly19750Ser	missense_variant	Exon 300 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes

AF:

0.0000987

AC:

AN:

152006

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.000221

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000109

AC:

AN:

248654

AF XY:

0.000104

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000145

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000558

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000187

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000294

AC:

430

AN:

1461298

Hom.:

Cov.:

AF XY:

0.000282

AC XY:

205

AN XY:

726942

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33448

American (AMR)

AF:

0.000112

AC:

AN:

44702

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26122

East Asian (EAS)

AF:

0.00

AC:

AN:

39656

South Asian (SAS)

AF:

0.0000232

AC:

AN:

86242

European-Finnish (FIN)

AF:

0.0000187

AC:

AN:

53402

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5760

European-Non Finnish (NFE)

AF:

0.000368

AC:

409

AN:

1111610

Other (OTH)

AF:

0.000199

AC:

AN:

60356

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.488

Heterozygous variant carriers

118

148

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

100

<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:

0.0000987

AC:

AN:

152006

Hom.:

Cov.:

AF XY:

0.0000539

AC XY:

AN XY:

74220

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41422

American (AMR)

AF:

0.00

AC:

AN:

15240

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5150

South Asian (SAS)

AF:

0.00

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10604

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000221

AC:

AN:

67982

Other (OTH)

AF:

0.00

AC:

AN:

2088

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.482

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:

0.000363

Hom.:

Bravo

AF:

0.000117

TwinsUK

AF:

0.00

AC:

ALSPAC

AF:

0.000519

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000486

AC:

ExAC

AF:

0.0000828

AC:

EpiCase

AF:

0.0000546

EpiControl

AF:

0.000119

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:9Benign:6

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:6Benign:1

Aug 21, 2024

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Missense variant in a gene in which most reported pathogenic variants are truncating/loss of function; Reported in published literature in an individual with dilated cardiomyopathy, an individual with hypertrophic cardiomyopathy, as well as in a healthy control (PMID: 23396983, 31983221); This variant is associated with the following publications: (PMID: 17344846, 23861362, 31983221, 34740920, 23396983) -

Dec 23, 2013

Genetic Services Laboratory, University of Chicago

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:research

- -

Apr 25, 2017

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 26, 2024

Athena Diagnostics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Available data are insufficient to determine the clinical significance of the variant at this time. The frequency of this variant in the general population is higher than would generally be expected for pathogenic variants in this gene. (http://gnomad.broadinstitute.org) Polyphen and MutationTaster yielded discordant predictions regarding whether this amino acid change is damaging to the protein. -

Aug 09, 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.59248G>A; p.Gly19750Ser variant (rs200732032; ClinVar Variation ID: 47248) is rare in the general population (<0.2% allele frequency in the Genome Aggregation Database). This variant is reported in the literature in an individual with dilated cardiomyopathy (DCM; Mazzarotto 2020) and in an individual with limb-girdle muscular dystrophy (Cloney 2022). 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.Gly19750Ser 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. Cloney T et al. Lessons learnt from multifaceted diagnostic approaches to the first 150 families in Victoria's Undiagnosed Diseases Program. J Med Genet. 2022 Aug;59(8):748-758. PMID: 34740920. 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. Mazzarotto F et al. Reevaluating the Genetic Contribution of Monogenic Dilated Cardiomyopathy. Circulation. 2020 Feb 4;141(5):387-398. PMID: 31983221. -

Feb 14, 2023

Revvity Omics, Revvity

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Autosomal recessive limb-girdle muscular dystrophy type 2J

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;C1858763:Dilated cardiomyopathy 1G

Uncertain:1

Oct 12, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

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

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

- -

Dilated cardiomyopathy 1G

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). Publications were found based on this search. The evidence from the literature, in combination with allele frequency data from public databases where available, was sufficient to determine this variant is unlikely to cause disease. Therefore, this variant is classified as likely 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. -

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. -

Cardiovascular phenotype

Benign:1

Feb 28, 2020

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 v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.14

BayesDel_addAF

Benign

-0.16

BayesDel_noAF

Benign

-0.21

CADD

Benign

(source)

DANN

Benign

0.93

Eigen

Pathogenic

0.95

Eigen_PC

Pathogenic

0.94

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.89

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

M_CAP

Benign

0.014

MetaRNN

Benign

0.40

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

MetaSVM

Uncertain

-0.17

MutationAssessor

Uncertain

2.4

.;.;.;M;.;.;M

PhyloP100

7.9

PrimateAI

Uncertain

0.64

PROVEAN

Pathogenic

-4.8

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

REVEL

Uncertain

0.45

Sift

Uncertain

0.0080

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

Polyphen

1.0

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

Vest4

0.59

MVP

0.45

MPC

0.45

ClinPred

0.24

GERP RS

6.2

Mutation Taster

=50/50

(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