rs143035953

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 1P and 9B. PP2BP4_StrongBP6BS1

The NM_001267550.2(TTN):c.8314G>A(p.Val2772Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000247 in 1,614,124 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 14/17 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.0010 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00016 ( 1 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3B:11

Conservation

PhyloP100: 1.33

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 made for transcript

Verdict is Benign. Variant got -8 ACMG points.

PP2

Missense variant where missense usually causes diseases, TTN

BP4

Computational evidence support a benign effect (MetaRNN=0.008017153).

BP6

Variant 2-178770478-C-T is Benign according to our data. Variant chr2-178770478-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 178269.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, Benign=4, Uncertain_significance=3}. Variant chr2-178770478-C-T is described in Lovd as [Benign]. Variant chr2-178770478-C-T is described in Lovd as [Likely_benign].

BS1

Variant frequency is greater than expected in population afr. gnomad4_exome allele frequency = 0.000163 (239/1461838) while in subpopulation AFR AF= 0.00478 (160/33480). AF 95% confidence interval is 0.00417. There are 1 homozygotes in gnomad4_exome. There are 101 alleles in male gnomad4_exome subpopulation. Median coverage is 33. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.8314G>A	p.Val2772Met	missense_variant	35/363	ENST00000589042.5
TTN	NM_133379.5 linkuse as main transcript	c.8314G>A	p.Val2772Met	missense_variant	35/46	ENST00000360870.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.8314G>A	p.Val2772Met	missense_variant	35/363	5	NM_001267550.2	P1
TTN	ENST00000360870.10 linkuse as main transcript	c.8314G>A	p.Val2772Met	missense_variant	35/46	5	NM_133379.5		Q8WZ42-6
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.1593-2797C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.00104

AC:

158

AN:

152168

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00355

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000327

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000577

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.000479

GnomAD3 exomes

AF:

0.000331

AC:

AN:

250914

Hom.:

AF XY:

0.000258

AC XY:

AN XY:

135584

show subpopulations

Gnomad AFR exome

AF:

0.00412

Gnomad AMR exome

AF:

0.0000868

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000327

Gnomad SAS exome

AF:

0.000131

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000177

Gnomad OTH exome

AF:

0.000163

GnomAD4 exome

AF:

0.000163

AC:

239

AN:

1461838

Hom.:

Cov.:

AF XY:

0.000139

AC XY:

101

AN XY:

727222

show subpopulations

Gnomad4 AFR exome

AF:

0.00478

Gnomad4 AMR exome

AF:

0.0000894

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.000529

Gnomad4 SAS exome

AF:

0.000139

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000261

Gnomad4 OTH exome

AF:

0.000215

GnomAD4 genome

AF:

0.00104

AC:

159

AN:

152286

Hom.:

Cov.:

AF XY:

0.00105

AC XY:

AN XY:

74464

show subpopulations

Gnomad4 AFR

AF:

0.00356

Gnomad4 AMR

AF:

0.000327

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000579

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.000474

Alfa

AF:

0.000164

Hom.:

Bravo

AF:

0.00121

ESP6500AA

AF:

0.00340

AC:

ESP6500EA

AF:

0.000116

AC:

ExAC

AF:

0.000329

AC:

Asia WGS

AF:

0.000867

AC:

AN:

3476

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3Benign:11

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Benign:4

Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Likely benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Sep 25, 2014	- -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Jul 29, 2015	p.Val2772Met in exon 35 of TTN: This variant is not expected to have clinical si gnificance because it has been identified in 0.3% (36/10404) of African chromoso mes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org/; dbSNP rs143035953). In addition, there is a lack of conservation across species, including mammals. Of note, myotis bat, microbat, big brown bat, and medaka, ha ve a Methionine (Met) at this position. -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 24, 2020	Variant summary: TTN c.8314G>A (p.Val2772Met) results in a conservative amino acid change located in the I-band region of the encoded protein sequence. Five of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00033 in 250914 control chromosomes, predominantly at a frequency of 0.0041 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 10-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. A co-occurrence with a pathogenic variant has been reported (TTR c.424G>A, p.V142I; Internal testing). Four ClinVar submitters (evaluation after 2014) cite the variant as benign/likely benign. One ClinVar submitter (evaluation after 2014) cites the variant as benign and as uncertain significance under different accession IDs. Based on the evidence outlined above, the variant was classified as benign. -

not provided

Benign:3

Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Aug 11, 2020	This variant is associated with the following publications: (PMID: 23861362) -
Likely benign, criteria provided, single submitter	research	Biesecker Lab/Clinical Genomics Section, National Institutes of Health	Jun 24, 2013	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

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. -

Dilated cardiomyopathy 1G

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

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

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Invitae

Jan 31, 2024

- -

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

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

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

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. -

Cardiovascular phenotype

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 13, 2018

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

0.10

BayesDel_addAF

Benign

-0.43

BayesDel_noAF

Benign

-0.39

Cadd

Benign

Dann

Benign

0.89

Eigen

Benign

-0.56

Eigen_PC

Benign

-0.52

FATHMM_MKL

Benign

0.082

LIST_S2

Uncertain

0.90

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

M_CAP

Benign

0.027

MetaRNN

Benign

0.0080

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

MetaSVM

Benign

-0.74

MutationTaster

Benign

1.0

N;N;N;N;N;N;N

PrimateAI

Benign

0.38

PROVEAN

Benign

-0.94

N;N;.;.;N;N;.;N

REVEL

Benign

0.14

Sift

Benign

0.10

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

Polyphen

0.013, 0.036

.;.;.;B;.;.;B;B

Vest4

0.28

MVP

0.41

MPC

0.084

ClinPred

0.0044

GERP RS

3.3

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

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over