rs374413644

Positions:

chr2-178615636-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PP3_Moderate

The NM_001267550.2(TTN):c.48460+5G>A variant causes a splice donor 5th base, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000285 in 1,611,980 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.00017 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

TTN
NM_001267550.2 splice_donor_5th_base, intron

Scores

Splicing: ADA: 0.9999

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:6

Conservation

PhyloP100: 7.77

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 Uncertain_significance. Variant got 2 ACMG points.

PP3

Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.48460+5G>A		splice_donor_5th_base_variant, intron_variant		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.48460+5G>A		splice_donor_5th_base_variant, intron_variant		5	NM_001267550.2	ENSP00000467141	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.502+17955C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.000171

AC:

AN:

151894

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000531

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000197

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:

0.00

Gnomad OTH

AF:

0.000478

GnomAD3 exomes

AF:

0.0000403

AC:

AN:

247848

Hom.:

AF XY:

0.0000223

AC XY:

AN XY:

134406

show subpopulations

Gnomad AFR exome

AF:

0.000583

Gnomad AMR exome

AF:

0.0000291

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000137

AC:

AN:

1460086

Hom.:

Cov.:

AF XY:

0.00000964

AC XY:

AN XY:

726304

show subpopulations

Gnomad4 AFR exome

AF:

0.000360

Gnomad4 AMR exome

AF:

0.0000448

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:

0.00000180

Gnomad4 OTH exome

AF:

0.0000664

GnomAD4 genome

AF:

0.000171

AC:

AN:

151894

Hom.:

Cov.:

AF XY:

0.000148

AC XY:

AN XY:

74152

show subpopulations

Gnomad4 AFR

AF:

0.000531

Gnomad4 AMR

AF:

0.000197

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.000478

Alfa

AF:

0.0000415

Hom.:

Bravo

AF:

0.000253

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Jan 18, 2019

Variant classified as Uncertain Significance - Favor Benign. The c.40756+5G>A variant in TTN has been identified in 1 African American individual with DCM. It has also been identified in 11/23996 of African chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs374413644). This variant has also been reported in ClinVar (Variation ID:178208). This variant is located in intron 207 in the 5' splice region. Computational tools suggest an impact to splicing; however, this information is not predictive enough to determine pathogenicity. Splice and other truncating variants in TTN are strongly associated with DCM and the majority occur in exons encoding for the A-band region of the protein (Herman 2012, Pugh 2014), where this variant is located. In summary, while there is some suspicion for a pathogenic role, the clinical significance of the c.40756+5G>A variant is uncertain. -

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

Jan 29, 2024

This sequence change falls in intron 258 of the TTN gene. It does not directly change the encoded amino acid sequence of the TTN protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (rs374413644, gnomAD 0.05%). 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: 178208). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant is located in the A band of TTN (PMID: 25589632). Variants in this region may be relevant for cardiac or neuromuscular disorders (PMID: 25589632, 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. -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1838244:Tibial muscular dystrophy;C1858763:Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure;C2673677:Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Apr 29, 2022

- -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Feb 17, 2023

Intronic +5 splice site variant in a gene for which loss of function is a known mechanism of disease, and splice predictors support a deleterious effect; Located in the A-band region of TTN in which the majority of loss of function variants have been associated with autosomal dominant titinopathies (Herman et al., 2012); This variant is associated with the following publications: (PMID: 22335739, 25589632) -

Primary dilated cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

research

Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust

Oct 08, 2014

This TTN truncating variant (TTNtv) was identified in four individuals in this cohort and is located in an exon that is highly expressed in the heart. In the seven cohorts assessed, TTNtv were found in 14% of ambulant DCM, 22% end-stage or familial DCM, and 2% controls. Heterozygous nonsense, frameshift and canonical splice-disrupting variants found in constitutive and other highly utilised exons are highly likely to be pathogenic when identified in individuals with phenotypically confirmed DCM. TTNtv found incidentally in healthy individuals (excluding familial assessment of DCM relatives) are thought to have low penetrance, particularly when identified in exons that are not constitutively expressed in the heart. -

Cardiovascular phenotype

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 15, 2023

The c.21265+5G>A intronic variant results from a G to A substitution 5 nucleotides after coding exon 85 in the TTN gene. This variant (referred to as c.48460+5G>A) has been detected in individuals from a community-based cohort; however, clinical details were limited (Roberts AM et al. Sci Transl Med, 2015 Jan;7:270ra6). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will result in the creation or strengthening of a novel splice donor site. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.27

CADD

Pathogenic

DANN

Benign

0.93

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

0.51

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.51

Position offset: 27

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