chr2-178725412-T-C

Position:

chr2-178725412-T-C

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 1P and 3B. PP2BP4_ModerateBP6

The NM_001267550.2(TTN):c.20792A>G(p.Asn6931Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000339 in 1,606,838 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.00025 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00035 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7B:7

Conservation

PhyloP100: 7.67

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 -2 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=0.15661943).

BP6

Variant 2-178725412-T-C is Benign according to our data. Variant chr2-178725412-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 282786.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=2, Uncertain_significance=7, Benign=2}. Variant chr2-178725412-T-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.20792A>G	p.Asn6931Ser	missense_variant	71/363	ENST00000589042.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris
TTN	ENST00000589042.5 linkuse as main transcript	c.20792A>G	p.Asn6931Ser	missense_variant	71/363	5	NM_001267550.2	P1
	ENST00000590024.1 linkuse as main transcript	n.1956T>C		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.503-9092T>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.000250

AC:

AN:

152202

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000121

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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:

0.000470

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000206

AC:

AN:

242304

Hom.:

AF XY:

0.000228

AC XY:

AN XY:

131344

show subpopulations

Gnomad AFR exome

AF:

0.0000654

Gnomad AMR exome

AF:

0.0000589

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000420

Gnomad OTH exome

AF:

0.000171

GnomAD4 exome

AF:

0.000348

AC:

506

AN:

1454518

Hom.:

Cov.:

AF XY:

0.000338

AC XY:

244

AN XY:

722758

show subpopulations

Gnomad4 AFR exome

AF:

0.000120

Gnomad4 AMR exome

AF:

0.0000452

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.000432

Gnomad4 OTH exome

AF:

0.000350

GnomAD4 genome

AF:

0.000249

AC:

AN:

152320

Hom.:

Cov.:

AF XY:

0.000242

AC XY:

AN XY:

74476

show subpopulations

Gnomad4 AFR

AF:

0.000120

Gnomad4 AMR

AF:

0.0000654

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.000470

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000442

Hom.:

Bravo

AF:

0.000253

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.00

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000602

AC:

ExAC

AF:

0.000215

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7Benign:7

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:3Benign:4

Uncertain significance, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Jul 28, 2019	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jun 13, 2018	- -
Likely benign, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Mar 30, 2021	This variant is associated with the following publications: (PMID: 25783436) -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Mar 31, 2023	- -

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. -

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

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 16, 2017

- -

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

not specified

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

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

Dec 29, 2020

Variant summary: TTN c.17060A>G (p.Asn5687Ser) results in a conservative amino acid change located in the I-band domain 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 0.00022 in 273704 control chromosomes, predominantly at a frequency of 0.00044 within the Non-Finnish European subpopulation in the gnomAD database. The observed variant frequency within Non-Finnish European control individuals in the gnomAD database is approximately 1.1 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 Non-Finnish European origin. c.17060A>G has been reported in the literature in one individual affected with distal myopathy (Sevy_2015). The report does not provide unequivocal conclusions about association of the variant with Dilated Cardiomyopathy. One co-occurrence with another pathogenic variant has been internally reported (LMNA c.725C>T, p.Ala242Val), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Five ClinVar submitters (evaluation after 2014) cite the variant as uncertain significance (3x), likely benign (1x) and benign (1x). Based on the evidence outlined above, the variant was classified as likely benign. -

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. -

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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.83

BayesDel_addAF

Benign

-0.25

BayesDel_noAF

Benign

-0.27

CADD

Benign

DANN

Benign

0.97

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.94

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.87

D;D;.;D

M_CAP

Benign

0.035

MetaRNN

Benign

0.16

T;T;T;T

MetaSVM

Uncertain

0.43

MutationTaster

Benign

0.90

D;D;D;D;D;D

PrimateAI

Uncertain

0.59

PROVEAN

Uncertain

-2.9

D;.;.;.

REVEL

Uncertain

0.63

Sift

Benign

0.15

T;.;.;.

Polyphen

1.0

.;.;D;D

Vest4

0.24

MVP

0.40

MPC

0.42

ClinPred

0.094

GERP RS

5.9

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