rs201623791

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 1P and 2B. PP2BP4BP6

The NM_001267550.2(TTN):c.54109C>T(p.Arg18037Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00011 in 1,612,392 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R18037Q) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000079 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00011 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7B:4

Conservation

PhyloP100: 3.21

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 -1 ACMG points.

PP2

Missense variant where missense usually causes diseases, TTN

BP4

Computational evidence support a benign effect (MetaRNN=0.30300277).

BP6

Variant 2-178605068-G-A is Benign according to our data. Variant chr2-178605068-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 229462.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=7, Likely_benign=4}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.54109C>T	p.Arg18037Trp	missense_variant	280/363	ENST00000589042.5
TTN-AS1	NR_038272.1 linkuse as main transcript	n.4255G>A		non_coding_transcript_exon_variant	17/17

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.54109C>T	p.Arg18037Trp	missense_variant	280/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.502+7387G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.0000790

AC:

AN:

151882

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000145

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000657

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:

0.0000736

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000525

AC:

AN:

247652

Hom.:

AF XY:

0.0000521

AC XY:

AN XY:

134336

show subpopulations

Gnomad AFR exome

AF:

0.0000648

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000327

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000894

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000114

AC:

166

AN:

1460510

Hom.:

Cov.:

AF XY:

0.000110

AC XY:

AN XY:

726556

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.0000448

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000116

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.000138

Gnomad4 OTH exome

AF:

0.000149

GnomAD4 genome

AF:

0.0000790

AC:

AN:

151882

Hom.:

Cov.:

AF XY:

0.0000539

AC XY:

AN XY:

74166

show subpopulations

Gnomad4 AFR

AF:

0.000145

Gnomad4 AMR

AF:

0.0000657

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000736

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000836

Hom.:

Bravo

AF:

0.000125

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000364

AC:

ExAC

AF:

0.0000414

AC:

EpiCase

AF:

0.000164

EpiControl

AF:

0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7Benign:4

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 27, 2020	Variant summary: TTN c.46405C>T (p.Arg15469Trp) results in a non-conservative amino acid change located in the A-band region 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 5.2e-05 in 247652 control chromosomes, predominantly at a frequency of 8.9e-05 within the Non-Finnish European subpopulation in the gnomAD database. However, in certain European subpopulations the variant occurs with an even higher frequency, e.g. in North-western Europeans (allele frequency: 0.0002). This frequency somewhat lower than the maximum expected for a pathogenic variant in TTN causing Dilated Cardiomyopathy (0.00039), allowing no clear conclusions about variant significance. The variant, c.46405C>T, has been reported in the literature in individuals affected with Dilated Cardiomyopathy (Horvat_2018, Minoche_2018, Mazzarotto_2020). However, in a reported family, this variant didn't segregate with the disease, while a pathogenic variant (MYH7 c.1106G>A, p.Arg369Gln), which could explain the phenotype, segregated with the disease (Horvat_2018, Minoche_2018); these data provide supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and classified the variant as VUS (3x) or likely benign (1x). Based on the evidence outlined above, the variant was classified as VUS-possibly benign. -
Uncertain significance, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Aug 03, 2017	The p.Arg15469Trp variant in TTN has not been previously reported in individuals with cardiomyopathy, but has been identified in 9/125506 European and 3/23972 A frican chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.bro adinstitute.org, dbSNP rs201623791). Computational prediction tools and conserva tion analysis suggest that this variant may impact the protein, though this info rmation is not predictive enough to determine pathogenicity. In summary, the cli nical significance of the p.Arg15469Trp variant is uncertain. -

not provided

Uncertain:1Benign:1

Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Sep 29, 2020	This variant is associated with the following publications: (PMID: 31983221) -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jul 10, 2019	- -

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

Invitae

May 10, 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

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Tibial muscular dystrophy

Benign:1

Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Cardiovascular phenotype

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 01, 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

Pathogenic

0.84

BayesDel_addAF

Benign

-0.15

BayesDel_noAF

Benign

-0.27

Cadd

Benign

Dann

Benign

0.93

Eigen

Uncertain

0.53

Eigen_PC

Uncertain

0.40

FATHMM_MKL

Uncertain

0.93

LIST_S2

Uncertain

0.97

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

M_CAP

Benign

0.037

MetaRNN

Benign

0.30

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

MetaSVM

Benign

-0.29

MutationTaster

Benign

1.0

D;D;D;D;D;D

PrimateAI

Uncertain

0.57

PROVEAN

Pathogenic

-6.1

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

REVEL

Uncertain

0.37

Sift

Uncertain

0.0010

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

Polyphen

1.0

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

Vest4

0.44

MVP

0.26

MPC

0.47

ClinPred

0.36

GERP RS

4.9

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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