2-178531663-T-G

Position:

chr2-178531663-T-G

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 1P and 2B. PP2BP4_Moderate

The NM_001267550.2(TTN):c.104952A>C(p.Glu34984Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000806 in 1,613,864 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000075 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:5

Conservation

PhyloP100: 0.0710

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 -1 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=0.08190495).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.104952A>C	p.Glu34984Asp	missense_variant	358/363	ENST00000589042.5	NP_001254479.2	A0A0A0MTS7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.104952A>C	p.Glu34984Asp	missense_variant	358/363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152178

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.00000753

AC:

AN:

1461686

Hom.:

Cov.:

AF XY:

0.00000688

AC XY:

AN XY:

727130

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

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:

0.00000809

Gnomad4 OTH exome

AF:

0.0000331

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152178

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74358

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000189

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Dec 23, 2022	BP4, PM2, PM3_supporting -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Oct 01, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Apr 27, 2023	Not observed at significant frequency in large population cohorts (gnomAD); Located in the M-line region of TTN in which the majority of loss of function variants have been associated with autosomal recessive titinopathies (Carmignac et al., 2007); Missense variant in a gene in which most reported pathogenic variants are truncating/loss of function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 17444505) -

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Athena Diagnostics

Sep 07, 2016

- -

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

Oct 09, 2023

This sequence change replaces glutamic acid, which is acidic and polar, with aspartic acid, which is acidic and polar, at codon 34984 of the TTN protein (p.Glu34984Asp). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TTN-related conditions. ClinVar contains an entry for this variant (Variation ID: 448766). Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. This variant is located in the M band of TTN (PMID: 25589632). Variants in this region may be relevant for neuromuscular disorders, but have not been definitively shown to cause cardiomyopathy (PMID: 23975875). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.37

BayesDel_addAF

Benign

-0.12

BayesDel_noAF

Benign

-0.41

CADD

Benign

9.3

DANN

Benign

0.91

Eigen

Benign

-0.67

Eigen_PC

Benign

-0.62

FATHMM_MKL

Benign

0.39

LIST_S2

Benign

0.79

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

M_CAP

Benign

0.031

MetaRNN

Benign

0.082

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

MetaSVM

Benign

-0.69

MutationAssessor

Benign

0.67

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

PrimateAI

Uncertain

0.63

PROVEAN

Benign

-2.0

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

REVEL

Benign

0.077

Sift

Benign

0.036

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

Polyphen

0.43

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

Vest4

0.27

MutPred

0.37

.;.;.;Loss of catalytic residue at E33343 (P = 0.1123);.;.;Loss of catalytic residue at E33343 (P = 0.1123);

MVP

0.18

MPC

0.10

ClinPred

0.15

GERP RS

1.6

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