2-178774337-A-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_ModerateBP6

The NM_001267550.2(TTN):c.6927T>A(p.Asn2309Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000118 in 1,614,086 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/19 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. N2309N) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000085 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000041 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3B:1

Conservation

PhyloP100: 1.57

Publications

2 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 -3 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.07963893).

BP6

Variant 2-178774337-A-T is Benign according to our data. Variant chr2-178774337-A-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 192073.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.6927T>A	p.Asn2309Lys	missense_variant	Exon 30 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.6927T>A	p.Asn2309Lys	missense_variant	Exon 30 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes

AF:

0.0000854

AC:

AN:

152150

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000314

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000239

AC:

AN:

251002

AF XY:

0.0000147

show subpopulations

Gnomad AFR exome

AF:

0.000369

Gnomad AMR exome

AF:

0.00

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:

0.00000410

AC:

AN:

1461818

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727216

show subpopulations

African (AFR)

AF:

0.000149

AC:

AN:

33474

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39696

South Asian (SAS)

AF:

0.00

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111954

Other (OTH)

AF:

0.0000166

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.508

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:

0.0000854

AC:

AN:

152268

Hom.:

Cov.:

AF XY:

0.000107

AC XY:

AN XY:

74450

show subpopulations

African (AFR)

AF:

0.000313

AC:

AN:

41554

American (AMR)

AF:

0.00

AC:

AN:

15294

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5186

South Asian (SAS)

AF:

0.00

AC:

AN:

4814

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10608

Middle Eastern (MID)

AF:

0.00

AC:

AN:

292

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68022

Other (OTH)

AF:

0.00

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.540

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:

0.00

Hom.:

Bravo

AF:

0.0000907

ESP6500AA

AF:

0.000681

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000576

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:1Benign:1

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:research

- -

Apr 06, 2020

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

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

Uncertain:1

Sep 04, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces asparagine with lysine at codon 2309 of the TTN protein (p.Asn2309Lys). There is a moderate physicochemical difference between asparagine and lysine. This variant is present in population databases (rs147580120, ExAC 0.07%). This variant has not been reported in the literature in individuals with TTN-related disease. ClinVar contains an entry for this variant (Variation ID: 192073). 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. -

Cardiovascular phenotype

Uncertain:1

Jun 18, 2019

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.N2263K variant (also known as c.6789T>A), located in coding exon 28 of the TTN gene, results from a T to A substitution at nucleotide position 6789. The asparagine at codon 2263 is replaced by lysine, an amino acid with similar properties. This alteration has been reported (as NM_133378.4:c.6927T>A p.N2309K) as a secondary cardiac variant in an exome cohort (Ng D et al. Circ Cardiovasc Genet, 2013 Aug;6:337-46). This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. 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

0.42

BayesDel_addAF

Benign

-0.40

BayesDel_noAF

Benign

-0.50

CADD

Benign

(source)

DANN

Benign

0.91

Eigen

Benign

-0.0013

Eigen_PC

Benign

0.0022

FATHMM_MKL

Uncertain

0.82

LIST_S2

Uncertain

0.88

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

M_CAP

Benign

0.0086

MetaRNN

Benign

0.080

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

MetaSVM

Benign

-0.95

PhyloP100

1.6

PrimateAI

Benign

0.46

PROVEAN

Uncertain

-3.6

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

REVEL

Benign

0.080

Sift

Benign

0.097

T;T;.;.;T;T;.;D

Sift4G

Uncertain

0.011

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

Polyphen

0.80, 0.99

.;.;.;P;.;.;P;D

Vest4

0.47

MutPred

0.53

Loss of ubiquitination at K2307 (P = 0.022);.;Loss of ubiquitination at K2307 (P = 0.022);Loss of ubiquitination at K2307 (P = 0.022);.;.;Loss of ubiquitination at K2307 (P = 0.022);Loss of ubiquitination at K2307 (P = 0.022);

MVP

0.099

MPC

0.20

ClinPred

0.13

GERP RS

0.40

Mutation Taster

=86/14

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