2-178555119-G-C

Position:

chr2-178555119-G-C

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 1P and 5B. PP2BP4_StrongBP6

The NM_001267550.2(TTN):c.88340C>G(p.Thr29447Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000138 in 1,613,188 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 14/19 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 0.00080 ( 1 hom., cov: 33)

Exomes 𝑓: 0.000069 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3B:8

Conservation

PhyloP100: 3.11

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:

(HGNC:):

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 Likely_benign. Variant got -4 ACMG points.

PP2

Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TTN. . Gene score misZ -1.1021 (greater than the threshold 3.09). Trascript score misZ 6.9794 (greater than threshold 3.09). GenCC has associacion of gene with dilated cardiomyopathy, tibial muscular dystrophy, early-onset myopathy with fatal cardiomyopathy, autosomal recessive centronuclear myopathy, hypertrophic cardiomyopathy, hypertrophic cardiomyopathy 9, TTN-related myopathy, dilated cardiomyopathy 1G, arrhythmogenic right ventricular cardiomyopathy, myopathy, myofibrillar, 9, with early respiratory failure, familial isolated dilated cardiomyopathy, childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome, autosomal recessive limb-girdle muscular dystrophy type 2J.

BP4

Computational evidence support a benign effect (MetaRNN=0.007935911).

BP6

Variant 2-178555119-G-C is Benign according to our data. Variant chr2-178555119-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 178176.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, Uncertain_significance=3, Benign=2}. Variant chr2-178555119-G-C is described in Lovd as [Likely_benign].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.88340C>G	p.Thr29447Arg	missense_variant	331/363	ENST00000589042.5
TTN-AS1	NR_038272.1 linkuse as main transcript	n.2043+12758G>C		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris
TTN	ENST00000589042.5 linkuse as main transcript	c.88340C>G	p.Thr29447Arg	missense_variant	331/363	5	NM_001267550.2	P1
	ENST00000624360.1 linkuse as main transcript	n.559G>C		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.416+31483G>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.000783

AC:

119

AN:

152036

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00271

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000459

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

GnomAD3 exomes

AF:

0.000198

AC:

AN:

247044

Hom.:

AF XY:

0.000119

AC XY:

AN XY:

134058

show subpopulations

Gnomad AFR exome

AF:

0.00305

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000558

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.000166

GnomAD4 exome

AF:

0.0000691

AC:

101

AN:

1461034

Hom.:

Cov.:

AF XY:

0.0000454

AC XY:

AN XY:

726750

show subpopulations

Gnomad4 AFR exome

AF:

0.00275

Gnomad4 AMR exome

AF:

0.0000448

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000252

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000180

Gnomad4 OTH exome

AF:

0.0000663

GnomAD4 genome

AF:

0.000795

AC:

121

AN:

152154

Hom.:

Cov.:

AF XY:

0.000807

AC XY:

AN XY:

74364

show subpopulations

Gnomad4 AFR

AF:

0.00275

Gnomad4 AMR

AF:

0.000458

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000147

Hom.:

Bravo

AF:

0.000963

ESP6500AA

AF:

0.00355

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.000240

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3Benign:8

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Benign:3

Likely benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jun 08, 2017	- -
Likely benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Oct 14, 2013	Thr26879Arg in exon 280 of TTN: This variant is not expected to have clinical si gnificance because it has been identified in 0.3% (13/3660) of African American chromosomes by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/ EVS/; dbSNP rs140201636). Thr26879Arg in exon 280 of TTN (rs140201636; allele f requency = 0.3%, 13/3660) ** -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Jan 18, 2017	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 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 13, 2018

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

TTN-related disorder

Benign:1

Likely benign, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

May 05, 2022

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

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 19, 2024

- -

Tibial muscular dystrophy

Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 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. -

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 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

Apr 11, 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

0.086

BayesDel_addAF

Benign

-0.37

BayesDel_noAF

Benign

-0.31

CADD

Benign

DANN

Benign

0.89

Eigen

Benign

0.032

Eigen_PC

Benign

0.21

FATHMM_MKL

Uncertain

0.95

LIST_S2

Benign

0.83

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

M_CAP

Benign

0.034

MetaRNN

Benign

0.0079

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

MetaSVM

Benign

-0.77

MutationAssessor

Benign

-1.1

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

MutationTaster

Benign

0.97

D;D;D;D;D;D

PrimateAI

Uncertain

0.57

PROVEAN

Uncertain

-3.4

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

REVEL

Benign

0.27

Sift

Benign

0.81

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

Polyphen

0.48

.;.;.;P;.;.;P

Vest4

0.44

MVP

0.30

MPC

0.20

ClinPred

0.040

GERP RS

4.8

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