rs397517580

Positions:

chr2-178621517-G-A

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1PP5_Very_Strong

The NM_001267550.2(TTN):c.45307C>T(p.Arg15103Ter) variant causes a stop gained change. The variant allele was found at a frequency of 0.00000496 in 1,612,220 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000048 ( 0 hom. )

Consequence

TTN
NM_001267550.2 stop_gained

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5U:1

Conservation

PhyloP100: 3.93

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 Pathogenic. Variant got 16 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PP5

Variant 2-178621517-G-A is Pathogenic according to our data. Variant chr2-178621517-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 46986.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178621517-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.45307C>T	p.Arg15103Ter	stop_gained	245/363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.45307C>T	p.Arg15103Ter	stop_gained	245/363	5	NM_001267550.2	ENSP00000467141	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.502+23836G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.00000659

AC:

AN:

151816

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.00000479

AC:

AN:

1460404

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

726500

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:

0.00000540

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.00000659

AC:

AN:

151816

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74100

show subpopulations

Gnomad4 AFR

AF:

0.00

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

Alfa

AF:

0.0000712

Hom.:

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Pathogenic:2Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Aug 10, 2023	Reported in association with cardiomyopathy and sudden death (Pugh et al., 2014; Walsh et al., 2017; Corden et al., 2019; Khera et al., 2019); Not observed at significant frequency in large population cohorts (gnomAD); Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Located in a region of TTN within the I-band in which the majority of loss of function variants are significantly associated with autosomal dominant titinopathies (Deo et al., 2016; Schafer et al., 2017); This variant is associated with the following publications: (PMID: 31983221, 31727422, 27532257, 27625338, 27869827, 35177841, 31251381, 24503780) -
Uncertain significance, no assertion criteria provided	provider interpretation	Stanford Center for Inherited Cardiovascular Disease, Stanford University	Sep 22, 2017	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Nov 30, 2021	PM2 -

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

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 22, 2024

This sequence change creates a premature translational stop signal (p.Arg15103*) in the TTN gene. While this is not anticipated to result in nonsense mediated decay, it is expected to create a truncated TTN protein. This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individuals with clinical features of centronuclear myopathy and/or dilated cardiomyopathy (PMID: 27532257, 31251381, 31727422, 31983221; Invitae). This variant is also known as p.Arg12535Ter. ClinVar contains an entry for this variant (Variation ID: 46986). This variant is located in the I band of TTN (PMID: 25589632). Truncating variants in this region have been reported in individuals affected with autosomal recessive centronuclear myopathy (PMID: 23975875, Invitae internal data). Truncating variants in this region have also been identified in individuals affected with autosomal dominant dilated cardiomyopathy and/or cardio-related conditions (PMID: 27869827, 32964742, Invitae internal data). For these reasons, this variant has been classified as Pathogenic. -

Primary dilated cardiomyopathy

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Aug 25, 2017

The p.Arg12535X variant in TTN has been identified by our laboratory in 1 indivi dual with DCM and segregated with disease in 2 affected relatives, including one obligate carrier. This variant was absent from large population studies. This n onsense variant leads to a premature termination codon at position 12535, which is predicted to lead to a truncated or absent protein. Nonsense and other trunca ting variants in TTN are strongly associated with DCM if they impact the exons e ncoding the A-band (Herman 2012, Pugh 2014) and/or are located in an exon that i s highly expressed in the heart (Roberts 2015). The p.Arg12535X variant is locat ed in the I-band in the highly expressed exon 194. In summary, although addition al studies are required to fully establish its clinical significance, the p.Arg1 2535X variant is likely pathogenic. ACMG/AMP Criteria applied: PVS1_Strong; PM2. -

Cardiovascular phenotype

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

May 07, 2024

The p.R6038* variant (also known as c.18112C>T), located in coding exon 72 of the TTN gene, results from a C to T substitution at nucleotide position 18112. This changes the amino acid from an arginine to a stop codon within coding exon 72. This exon is located in the I-band region of the N2-B isoform of the titin protein and is constitutively expressed in TTN transcripts (percent spliced in or PSI 100%). This alteration was reported in one individual with dilated cardiomyopathy (DCM) (Pugh TJ et al. Genet. Med., 2014 Aug;16:601-8). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. While truncating variants in TTN are present in 1-3% of the general population, truncating variants in the A-band are the most common cause of dilated cardiomyopathy (DCM) (Herman DS et al. N. Engl. J. Med., 2012 Feb;366:619-28; Roberts AM et al. Sci Transl Med, 2015 Jan;7:270ra6). TTN truncating variants encoded in constitutive exons (PSI >90%) have been found to be significantly associated with DCM regardless of their position in titin (Schafer S et al. Nat. Genet., 2017 01;49:46-53). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). As such, this alteration is classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.61

BayesDel_noAF

Pathogenic

0.63

CADD

Pathogenic

DANN

Uncertain

0.98

Eigen

Pathogenic

0.92

Eigen_PC

Pathogenic

0.74

FATHMM_MKL

Pathogenic

0.97

MutationTaster

Benign

1.0

A;A;A;A;A;A

Vest4

0.92

GERP RS

3.0

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