2-178532201-C-T

Variant summary

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

The NM_001267550.2(TTN):c.104414G>A(p.Arg34805Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000127 in 1,613,520 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R34805L) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00016 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00012 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5B:4

Conservation

PhyloP100: 0.134

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 Likely_benign. Variant got -4 ACMG points.

PP2

Missense variant where missense usually causes diseases, TTN

BP4

Computational evidence support a benign effect (MetaRNN=0.018333495).

BP6

Variant 2-178532201-C-T is Benign according to our data. Variant chr2-178532201-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 203080.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Benign=1, Uncertain_significance=5}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.104414G>A	p.Arg34805Gln	missense_variant	358/363	ENST00000589042.5
TTN-AS1	NR_038272.1 linkuse as main transcript	n.220-3531C>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.104414G>A	p.Arg34805Gln	missense_variant	358/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.416+8565C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.000158

AC:

AN:

152170

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:

0.0000942

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000294

Gnomad OTH

AF:

0.000478

GnomAD3 exomes

AF:

0.000133

AC:

AN:

247298

Hom.:

AF XY:

0.000142

AC XY:

AN XY:

134164

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000116

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000327

Gnomad FIN exome

AF:

0.0000470

Gnomad NFE exome

AF:

0.000242

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000124

AC:

181

AN:

1461232

Hom.:

Cov.:

AF XY:

0.000113

AC XY:

AN XY:

726918

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000134

Gnomad4 ASJ exome

AF:

0.0000383

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000464

Gnomad4 FIN exome

AF:

0.0000189

Gnomad4 NFE exome

AF:

0.000146

Gnomad4 OTH exome

AF:

0.000116

GnomAD4 genome

AF:

0.000158

AC:

AN:

152288

Hom.:

Cov.:

AF XY:

0.000175

AC XY:

AN XY:

74468

show subpopulations

Gnomad4 AFR

AF:

0.0000481

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.0000942

Gnomad4 NFE

AF:

0.000294

Gnomad4 OTH

AF:

0.000473

Alfa

AF:

0.000218

Hom.:

Bravo

AF:

0.0000869

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000121

AC:

ExAC

AF:

0.000132

AC:

EpiCase

AF:

0.000273

EpiControl

AF:

0.000237

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:5Benign:4

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:3Benign:2

Uncertain significance, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	May 17, 2023	BP4 -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Dec 29, 2020	- -
Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	May 01, 2022	TTN: BP4 -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Sep 15, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jun 02, 2017	- -

not specified

Uncertain:1Benign:1

Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Jun 02, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 16, 2024	Variant summary: TTN c.96710G>A (p.Arg32237Gln) results in a conservative amino acid change located in the M-band region of the encoded protein sequence. Four of four in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00013 in 247298 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in TTN causing Dilated Cardiomyopathy (0.00013 vs 0.00039), allowing no conclusion about variant significance. To our knowledge, no occurrence of c.96710G>A in individuals affected with Dilated Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. ClinVar contains an entry for this variant (Variation ID: 203080. VUS, n=4; Benign/likely benign, n=4). Based on the evidence outlined above, the variant was classified as uncertain significance. -

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

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 22, 2017

- -

Cardiovascular phenotype

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 17, 2022

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

0.093

BayesDel_addAF

Benign

-0.45

BayesDel_noAF

Benign

-0.47

Cadd

Benign

3.5

Dann

Benign

0.82

Eigen

Benign

-0.82

Eigen_PC

Benign

-0.74

FATHMM_MKL

Benign

0.46

LIST_S2

Benign

0.77

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

M_CAP

Benign

0.044

MetaRNN

Benign

0.018

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

MetaSVM

Benign

-0.95

MutationTaster

Benign

1.0

N;N;N;N;N;N

PrimateAI

Benign

0.22

PROVEAN

Benign

-2.0

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

REVEL

Benign

0.044

Sift

Benign

0.048

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

Polyphen

0.041

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

Vest4

0.11

MVP

0.067

MPC

0.097

ClinPred

0.046

GERP RS

0.78

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

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