chr2-178746072-A-G

Position:

chr2-178746072-A-G

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4_StrongBP6

The NM_133379.5(TTN):c.16328T>C(p.Val5443Ala) variant causes a missense change. The variant allele was found at a frequency of 0.000424 in 1,613,446 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/15 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 0.00041 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00042 ( 0 hom. )

Consequence

TTN
NM_133379.5 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:5

Conservation

PhyloP100: 6.04

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:):

TTN-AS1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -5 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.05226916).

BP6

Variant 2-178746072-A-G is Benign according to our data. Variant chr2-178746072-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47799.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=2, Uncertain_significance=2}. Variant chr2-178746072-A-G is described in Lovd as [Likely_benign].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_133379.5 linkuse as main transcript	c.16328T>C	p.Val5443Ala	missense_variant	46/46	ENST00000360870.10	NP_596870.2	Q8WZ42-6Q7Z3B7
TTN	NM_001267550.2 linkuse as main transcript	c.11312-4151T>C		intron_variant		ENST00000589042.5	NP_001254479.2	A0A0A0MTS7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000360870.10 linkuse as main transcript	c.16328T>C	p.Val5443Ala	missense_variant	46/46	5	NM_133379.5	ENSP00000354117.4		Q8WZ42-6
TTN	ENST00000589042.5 linkuse as main transcript	c.11312-4151T>C		intron_variant		5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.000414

AC:

AN:

152000

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

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:

0.000282

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000839

Gnomad OTH

AF:

0.000479

GnomAD3 exomes

AF:

0.000348

AC:

AN:

250316

Hom.:

AF XY:

0.000281

AC XY:

AN XY:

135234

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.000185

Gnomad NFE exome

AF:

0.000647

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000425

AC:

621

AN:

1461328

Hom.:

Cov.:

AF XY:

0.000399

AC XY:

290

AN XY:

726982

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000313

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.000187

Gnomad4 NFE exome

AF:

0.000526

Gnomad4 OTH exome

AF:

0.000199

GnomAD4 genome

AF:

0.000414

AC:

AN:

152118

Hom.:

Cov.:

AF XY:

0.000390

AC XY:

AN XY:

74386

show subpopulations

Gnomad4 AFR

AF:

0.0000482

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.000282

Gnomad4 NFE

AF:

0.000839

Gnomad4 OTH

AF:

0.000474

Alfa

AF:

0.000571

Hom.:

Bravo

AF:

0.000298

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.000259

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000581

AC:

ExAC

AF:

0.000321

AC:

EpiCase

AF:

0.000655

EpiControl

AF:

0.000474

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:5

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:1Benign:4

Likely benign, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jul 11, 2018	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Mar 02, 2021	- -

TTN-related myopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Feb 02, 2022

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as VUS-3C. Following criteria are met: 0102 - Loss of function is known mechanism of disease in this gene. In addition, dominant-negative is also a suggested mechanism as not all truncated transcripts in dilated cardiomyopathy (DCM) undergo nonsense mediated decay (PMID: 25589632). (I) 0108 - This gene is associated with both recessive and dominant disease (OMIM). (I) 0112 - The condition associated with this gene has incomplete penetrance. Protein truncating variants in this gene are known to have reduced penetrance in DCM (PMID: 25589632). (I) 0200 - Variant is predicted to result in a missense amino acid change from valine to alanine. (I) 0219 - This variant is non-coding in an alternative transcript. It is coding only in NM_133379.4, the novex-3 isoform, which is mainly expressed in sarcomeres, but also has been found in skeletal muscle (PMID: 11717165, 28510117) and it is noncoding in all other transcripts including the NM_133378.4, the predominant isoform in skeletal muscle (NCBI). (I) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD (v2) <0.01 for a recessive condition (100 heterozygotes, 0 homozygotes). (SP) 0503 - Missense variant consistently predicted to be tolerated by multiple in silico tools or not conserved in placental mammals with a minor amino acid change. (SB) 0604 - Variant is not located in an established domain, motif, hotspot or informative constraint region. (I) 0705 - No comparable missense variants have previous evidence for pathogenicity. (I) 0808 - Previous reports of pathogenicity for this variant are conflicting. It has been identified in an individual with Leigh syndrome, who also harboured many other variants including the p.(Val5443Ala) in the TTN gene, however phenotype was not regarded as a match (Lake, N.J. (2018)). In addition, it has been reported as a VUS (ClinVar) and likely benign (LOVD). (I) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

not specified

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

May 06, 2021

The p.Val5443Ala variant in TTN is classified as likely benign because it has been identified in 0.065% (84/128194) of European chromosomes by gnomAD (http://gnomad.broadinstitute.org). It is also located in an exon that is not highly expressed in the heart and is only present in a transcript (Novex -3) whose function is unclear. ACMG/AMP Criteria applied: BP1, BS1. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Benign

-0.37

BayesDel_noAF

Benign

-0.39

CADD

Benign

DANN

Benign

0.90

Eigen

Benign

-0.27

Eigen_PC

Benign

-0.18

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.34

M_CAP

Benign

0.022

MetaRNN

Benign

0.052

MetaSVM

Benign

-0.88

MutationTaster

Benign

1.0

D;D;D;D;D;D;N

PROVEAN

Benign

-0.86

REVEL

Benign

0.20

Sift

Benign

0.49

Sift4G

Benign

0.44

Polyphen

0.075

Vest4

0.24

MVP

0.64

ClinPred

0.055

GERP RS

6.1

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