chr2-178620456-C-G

Variant names:

Variant summary

Our verdict is Benign. The variant received -13 ACMG points: 0P and 13B. BP4_StrongBP6BS1BS2

The NM_001267550.2(TTN):c.46065G>C(p.Lys15355Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000135 in 1,612,370 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts 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. K15355K) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000086 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00014 ( 2 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:8B:5

Conservation

PhyloP100: -0.131

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: Benign. The variant received -13 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.013557643).

BP6

Variant 2-178620456-C-G is Benign according to our data. Variant chr2-178620456-C-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 46995.

BS1

Variant frequency is greater than expected in population sas. GnomAd4 allele frequency = 0.0000855 (13/151998) while in subpopulation SAS AF = 0.00269 (13/4828). AF 95% confidence interval is 0.00159. There are 0 homozygotes in GnomAd4. There are 10 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

BS2

High Homozygotes in GnomAdExome4 at 2 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.46065G>C	p.Lys15355Asn	missense_variant	Exon 248 of 363	ENST00000589042.5	NP_001254479.2	A0A0A0MTS7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.46065G>C	p.Lys15355Asn	missense_variant	Exon 248 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.0000856

AC:

AN:

151880

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:

0.00269

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000299

AC:

AN:

247648

AF XY:

0.000417

show subpopulations

Gnomad AFR exome

AF:

0.00

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:

0.000140

AC:

205

AN:

1460372

Hom.:

Cov.:

AF XY:

0.000209

AC XY:

152

AN XY:

726482

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33380

American (AMR)

AF:

0.00

AC:

AN:

44642

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26070

East Asian (EAS)

AF:

0.00

AC:

AN:

39588

South Asian (SAS)

AF:

0.00232

AC:

200

AN:

86186

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53376

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5752

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111082

Other (OTH)

AF:

0.0000829

AC:

AN:

60296

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.467

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome 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

GnomAD4 genome

AF:

0.0000855

AC:

AN:

151998

Hom.:

Cov.:

AF XY:

0.000135

AC XY:

AN XY:

74304

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41528

American (AMR)

AF:

0.00

AC:

AN:

15228

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5130

South Asian (SAS)

AF:

0.00269

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67878

Other (OTH)

AF:

0.00

AC:

AN:

2108

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

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:

0.0000434

Hom.:

Bravo

AF:

0.0000151

ExAC

AF:

0.000331

AC:

Asia WGS

AF:

0.000578

AC:

AN:

3476

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:8Benign:5

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:1Benign:1

Dec 18, 2015

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.Lys12787Asn v ariant in TTN has been reported by our laboratory in 2 individuals (1 HCM and 1 ARVC with reduced LV function). Both individuals carried a disease-causing varia nt in another gene and p.Lys12787Asn did not segregate with ARVC in an affected family member. It has been identified in 0.24% (40/16444) of South Asian chromo somes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs397517583). Computational prediction tools and conservation analysis su ggest that this variant may impact the protein, though this information is not p redictive enough to determine pathogenicity. In summary, while the clinical sign ificance of the p.Lys12787Asn variant is uncertain, its frequency suggests that it is more likely to be benign. -

Nov 17, 2020

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

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: TTN c.38361G>C (p.Lys12787Asn) results in a non-conservative amino acid change located in the I-band region of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.0003 in 247648 control chromosomes, predominantly at a frequency of 0.0024 within the South Asian subpopulation in the gnomAD database, including 1 homozygote. The observed variant frequency within South Asian 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 South Asian origin. The variant, c.38361G>C, has been reported in the literature in an individual affected with Dilated Cardiomyopathy, however this patient also had Wolff-Parkinson-White (WPW) syndrome and glycogen accumulation noted during cardiac transplant, consistent with Danon disease, in addition, in this patient a co-occurrence with another pathogenic variant (LAMP2 exon8-9 del) could explain the disease phenotype (Ceyhan-Birsoy_2015). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. Multiple laboratories reported the variant with conflicting assessments (benign (1x), likely benign (1x), VUS (3x)). Based on the evidence outlined above, the variant was classified as benign. -

not provided

Uncertain:1Benign:1

Mar 23, 2017

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jan 08, 2021

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Limb-girdle muscular dystrophy, recessive

Uncertain:1

Jun 14, 2016

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

Jun 14, 2016

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Dilated Cardiomyopathy, Dominant

Uncertain:1

Jun 14, 2016

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Tibial muscular dystrophy

Uncertain:1

Jun 14, 2016

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Myopathy, myofibrillar, 9, with early respiratory failure

Uncertain:1

Jun 14, 2016

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Hypertrophic cardiomyopathy

Uncertain:1

Jun 14, 2016

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

TTN-related disorder

Benign:1

Jul 28, 2022

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 23, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Cardiomyopathy

Benign:1

Oct 17, 2017

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.81

BayesDel_addAF

Benign

-0.46

BayesDel_noAF

Benign

-0.43

CADD

Benign

(source)

DANN

Benign

0.59

Eigen

Benign

-0.10

Eigen_PC

Benign

-0.26

FATHMM_MKL

Benign

0.68

LIST_S2

Uncertain

0.94

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

M_CAP

Benign

0.021

MetaRNN

Benign

0.014

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

MetaSVM

Uncertain

-0.26

MutationAssessor

Uncertain

2.5

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

PhyloP100

-0.13

PrimateAI

Uncertain

0.60

PROVEAN

Uncertain

-3.2

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

REVEL

Uncertain

0.31

Sift

Benign

0.087

T;T;.;.;T;T;.

Polyphen

1.0

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

Vest4

0.56

MutPred

0.57

.;.;.;Loss of ubiquitination at K13714 (P = 0.0309);.;.;Loss of ubiquitination at K13714 (P = 0.0309);

MVP

0.24

MPC

0.47

ClinPred

0.20

GERP RS

-0.15

Mutation Taster

=99/1

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