2-178614664-C-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP6

The NM_001267550.2(TTN):c.48850G>A(p.Gly16284Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000403 in 1,612,238 control chromosomes in the GnomAD database, including 1 homozygotes. 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. G16284E) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000020 ( 1 hom., cov: 32)

Exomes 𝑓: 0.000042 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

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

Conservation

PhyloP100: 7.79

Publications

3 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 -1 ACMG points.

BP6

Variant 2-178614664-C-T is Benign according to our data. Variant chr2-178614664-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 535028.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.48850G>A	p.Gly16284Arg	missense_variant	Exon 261 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.48850G>A	p.Gly16284Arg	missense_variant	Exon 261 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes

AF:

0.0000198

AC:

AN:

151810

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:

0.000414

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.000480

GnomAD2 exomes

AF:

0.0000323

AC:

AN:

247404

AF XY:

0.0000447

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000291

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000358

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000425

AC:

AN:

1460310

Hom.:

Cov.:

AF XY:

0.0000427

AC XY:

AN XY:

726458

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33396

American (AMR)

AF:

0.0000672

AC:

AN:

44618

Ashkenazi Jewish (ASJ)

AF:

0.0000383

AC:

AN:

26094

East Asian (EAS)

AF:

0.00

AC:

AN:

39456

South Asian (SAS)

AF:

0.000104

AC:

AN:

86206

European-Finnish (FIN)

AF:

0.0000187

AC:

AN:

53350

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5752

European-Non Finnish (NFE)

AF:

0.0000396

AC:

AN:

1111162

Other (OTH)

AF:

0.0000664

AC:

AN:

60276

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.477

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:

0.0000197

AC:

AN:

151928

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74248

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41488

American (AMR)

AF:

0.00

AC:

AN:

15250

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3464

East Asian (EAS)

AF:

0.00

AC:

AN:

5110

South Asian (SAS)

AF:

0.000415

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10590

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67890

Other (OTH)

AF:

0.000475

AC:

AN:

2106

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Hom

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:

0.0000494

Hom.:

Bravo

AF:

0.00000378

ESP6500AA

AF:

0.000268

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000166

AC:

EpiCase

AF:

0.00

EpiControl

AF:

0.000119

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:6Benign:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Dec 04, 2021

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

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

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

Uncertain:1

Feb 11, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces glycine with arginine at codon 16284 of the TTN protein (p.Gly16284Arg). There is a moderate physicochemical difference between glycine and arginine. This variant is present in population databases (rs368527534, ExAC 0.01%). This variant has not been reported in the literature in individuals with TTN-related disease. This variant identified in the TTN gene is located in the A band of the resulting protein (PMID: 25589632). It is unclear how this variant impacts the function of this protein. Algorithms developed to predict the effect of missense changes on protein structure and function are unavailable for the TTN gene. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Dilated cardiomyopathy 1G

Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Cardiovascular phenotype

Uncertain:1

Nov 27, 2019

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.G7219R variant (also known as c.21655G>A), located in coding exon 88 of the TTN gene, results from a G to A substitution at nucleotide position 21655. The glycine at codon 7219 is replaced by arginine, an amino acid with dissimilar 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. -

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Tibial muscular dystrophy

Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

1.0

BayesDel_addAF

Uncertain

0.10

BayesDel_noAF

Uncertain

0.11

CADD

Uncertain

(source)

DANN

Benign

0.95

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.96

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

M_CAP

Uncertain

0.10

MetaRNN

Uncertain

0.65

D;D;D;D;D;D;D

MetaSVM

Pathogenic

0.92

MutationAssessor

Pathogenic

4.3

.;.;.;H;.;.;H

PhyloP100

7.8

PrimateAI

Uncertain

0.71

PROVEAN

Pathogenic

-6.0

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

REVEL

Pathogenic

0.82

Sift

Pathogenic

0.0

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

Polyphen

1.0

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

Vest4

0.59

MutPred

0.91

.;.;.;Loss of ubiquitination at K14648 (P = 0.0424);.;.;Loss of ubiquitination at K14648 (P = 0.0424);

MVP

0.89

MPC

0.51

ClinPred

0.73

GERP RS

5.6

Mutation Taster

=51/49

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