rs72648206

Variant summary

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

The NM_001267550.2(TTN):c.79226G>A(p.Arg26409His) variant causes a missense change. The variant allele was found at a frequency of 0.000858 in 1,613,590 control chromosomes in the GnomAD database, including 4 homozygotes. In-silico tool predicts 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. R26409C) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00067 ( 1 hom., cov: 33)

Exomes 𝑓: 0.00088 ( 3 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:9B:8

Conservation

PhyloP100: 3.95

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 -2 ACMG points.

PP2

Missense variant where missense usually causes diseases, TTN

BP4

Computational evidence support a benign effect (MetaRNN=0.09763107).

BP6

Variant 2-178566906-C-T is Benign according to our data. Variant chr2-178566906-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47372.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=6, Uncertain_significance=9, Benign=2}. Variant chr2-178566906-C-T is described in Lovd as [Benign]. Variant chr2-178566906-C-T 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.79226G>A	p.Arg26409His	missense_variant	326/363	ENST00000589042.5
TTN-AS1	NR_038272.1 linkuse as main transcript	n.2044-15666C>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.79226G>A	p.Arg26409His	missense_variant	326/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.417-30690C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.000671

AC:

102

AN:

152098

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000169

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000197

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000387

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00129

Gnomad OTH

AF:

0.000478

GnomAD3 exomes

AF:

0.000544

AC:

135

AN:

248190

Hom.:

AF XY:

0.000460

AC XY:

AN XY:

134662

show subpopulations

Gnomad AFR exome

AF:

0.000130

Gnomad AMR exome

AF:

0.000116

Gnomad ASJ exome

AF:

0.000299

Gnomad EAS exome

AF:

0.000223

Gnomad SAS exome

AF:

0.000392

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000963

Gnomad OTH exome

AF:

0.000332

GnomAD4 exome

AF:

0.000877

AC:

1282

AN:

1461374

Hom.:

Cov.:

AF XY:

0.000861

AC XY:

626

AN XY:

726992

show subpopulations

Gnomad4 AFR exome

AF:

0.000179

Gnomad4 AMR exome

AF:

0.000112

Gnomad4 ASJ exome

AF:

0.0000766

Gnomad4 EAS exome

AF:

0.000101

Gnomad4 SAS exome

AF:

0.000406

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00108

Gnomad4 OTH exome

AF:

0.000464

GnomAD4 genome

AF:

0.000670

AC:

102

AN:

152216

Hom.:

Cov.:

AF XY:

0.000685

AC XY:

AN XY:

74410

show subpopulations

Gnomad4 AFR

AF:

0.000168

Gnomad4 AMR

AF:

0.000196

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000388

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00129

Gnomad4 OTH

AF:

0.000473

Alfa

AF:

0.000820

Hom.:

Bravo

AF:

0.000570

TwinsUK

AF:

0.00162

AC:

ALSPAC

AF:

0.000778

AC:

ESP6500AA

AF:

0.000268

AC:

ESP6500EA

AF:

0.00158

AC:

ExAC

AF:

0.000604

AC:

Asia WGS

AF:

0.00751

AC:

AN:

3478

EpiCase

AF:

0.00104

EpiControl

AF:

0.000415

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:9Benign:8

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:3Benign:4

Likely benign, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Sep 15, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Mar 20, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Dec 15, 2017	- -
Likely benign, criteria provided, single submitter	research	Biesecker Lab/Clinical Genomics Section, National Institutes of Health	Jun 24, 2013	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Oct 28, 2020	This variant is associated with the following publications: (PMID: 23861362) -
Likely benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Jul 15, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Oct 01, 2019	- -

not specified

Uncertain:1Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Jun 13, 2016	Variant classified as Uncertain Significance - Favor Benign. -
Likely benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 14, 2021	Variant summary: TTN c.71522G>A (p.Arg23841His) results in a non-conservative amino acid change located in the A-band domain of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00054 in 248190 control chromosomes, predominantly at a frequency of 0.00096 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 2.5 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.71522G>A has been reported in the literature in two individuals affected with Arrhythmogenic Right Ventricular Cardiomyopathy (Campuzano_2015). These reports do not provide unequivocal conclusions about association of the variant with Dilated Cardiomyopathy. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Nine ClinVar submitters (evaluation after 2014) cite the variant as uncertain significance (n=6), likely benign (n=2) and benign (n=1). Based on the evidence outlined above, the variant was classified as likely benign. -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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

Invitae

Dec 18, 2017

- -

Dilated cardiomyopathy 1G

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

Cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Center for Advanced Laboratory Medicine, UC San Diego Health, University of California San Diego

Feb 11, 2018

- -

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

Tibial muscular dystrophy

Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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 12, 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

Jul 15, 2019

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

0.22

BayesDel_addAF

Benign

-0.38

BayesDel_noAF

Benign

-0.31

Cadd

Uncertain

Dann

Benign

0.89

Eigen

Uncertain

0.68

Eigen_PC

Uncertain

0.65

FATHMM_MKL

Uncertain

0.96

LIST_S2

Uncertain

0.86

D;T;T;.;D;T;D

M_CAP

Benign

0.023

MetaRNN

Benign

0.098

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

MetaSVM

Benign

-0.30

MutationTaster

Benign

1.0

D;D;D;D;D;D

PrimateAI

Uncertain

0.72

PROVEAN

Uncertain

-3.3

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

REVEL

Uncertain

0.35

Sift

Benign

0.031

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

Polyphen

1.0

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

Vest4

0.42

MVP

0.37

MPC

0.50

ClinPred

0.064

GERP RS

4.9

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