2-178546600-C-T

Variant names:

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PP3_Strong

The NM_001267550.2(TTN):c.94828G>A(p.Ala31610Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000355 in 1,606,122 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/23 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000036 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Splicing: ADA: 1.000

Clinical Significance

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

Conservation

PhyloP100: 1.57

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 4 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 rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.94828G>A	p.Ala31610Thr	missense_variant	Exon 341 of 363	ENST00000589042.5	NP_001254479.2	A0A0A0MTS7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.94828G>A	p.Ala31610Thr	missense_variant	Exon 341 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152096

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:

0.000770

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000937

AC:

AN:

245388

Hom.:

AF XY:

0.0000751

AC XY:

AN XY:

133102

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000292

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00118

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000904

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000365

AC:

AN:

1453908

Hom.:

Cov.:

AF XY:

0.0000305

AC XY:

AN XY:

721724

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000675

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.000837

Gnomad4 SAS exome

AF:

0.0000117

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000136

Gnomad4 OTH exome

AF:

0.0000167

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152214

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74400

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000772

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000166

Hom.:

Bravo

AF:

0.0000567

ExAC

AF:

0.0000662

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Uncertain:1

May 04, 2012

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The Ala29042Thr variant in TTN has not been reported in the literature nor previ ously identified by our laboratory. This variant has not been identified in a ve ry large and broad population by the NHLBI Exome Sequencing Project (http://evs. gs.washington.edu/EVS). This low frequency is consistent with a disease causing role but insufficient to establish this with confidence. Alanine (Ala) at positi on 29042 is not well conserved in evolution, suggesting that a change would be t olerated. However, this variant is located in the last bases of the exon, which is part of the 5? splice region. Computational tools predict a possible effect on splicing, though the accuracy of these tools is unknown. Other computational analyses (biochemical amino acid properties, AlignGVGD, PolyPhen2, and SIFT) do not provide strong support for or against an impact to the protein. Additional i nformation is needed to fully assess the clinical significance of the Ala29042Th r variant -

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

Uncertain:1

Nov 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 31610 of the TTN protein (p.Ala31610Thr). This variant also falls at the last nucleotide of exon 341, which is part of the consensus splice site for this exon. This variant is present in population databases (rs141357723, gnomAD 0.1%). 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: 47543). Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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. -

Cardiomyopathy

Uncertain:1

Jun 08, 2018

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

Nov 17, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided

Uncertain:1

Sep 30, 2013

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiovascular phenotype

Uncertain:1

Oct 02, 2019

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.A22545T variant (also known as c.67633G>A), located in coding exon 168 of the TTN gene, results from a G to A substitution at nucleotide position 67633. The amino acid change results in alanine to threonine at codon 22545, an amino acid with similar properties. This change occurs in the last base pair of coding exon 168, which makes it likely to have some effect on normal mRNA splicing. Using two different splice site prediction tools, this alteration is predicted by BDGP to abolish the native splice donor site, and is predicted to weaken (but not abolish) the efficiency of the native splice donor site by ESEfinder; however, direct evidence is unavailable. The nucleotide and amino acid positions are not well conserved in available vertebrate species, and threonine is the reference amino acid in other vertebrate species. In addition, the amino acid change is predicted to be tolerated by in silico analysis. 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

AlphaMissense

Benign

0.071

BayesDel_addAF

Benign

-0.44

BayesDel_noAF

Benign

-0.45

CADD

Uncertain

DANN

Benign

0.84

Eigen

Benign

-0.19

Eigen_PC

Benign

-0.020

FATHMM_MKL

Benign

0.75

LIST_S2

Benign

0.81

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

M_CAP

Benign

0.013

MetaRNN

Benign

0.013

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

MetaSVM

Benign

-1.0

MutationAssessor

Benign

0.94

.;.;.;L;.;.;L

PrimateAI

Benign

0.43

PROVEAN

Benign

-1.4

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

REVEL

Benign

0.025

Sift

Benign

0.39

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

Polyphen

0.0070

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

Vest4

0.095

MVP

0.23

MPC

0.082

ClinPred

0.042

GERP RS

4.0

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

1.0

SpliceAI score (max)

0.75

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.75

Position offset: 0

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