2-178779279-C-A

Position:

chr2-178779279-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 1P and 0B. PP2

The NM_001267550.2(TTN):c.3913G>T(p.Gly1305Trp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000403 in 1,613,724 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. G1305R) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000042 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:9B:1

Conservation

PhyloP100: 7.88

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:

LOC101927055 (HGNC:):

LOC101927055 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 1 ACMG points.

PP2

Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TTN. . Gene score misZ -1.1021 (greater than the threshold 3.09). Trascript score misZ 6.9794 (greater than threshold 3.09). GenCC has associacion of gene with dilated cardiomyopathy, tibial muscular dystrophy, early-onset myopathy with fatal cardiomyopathy, autosomal recessive centronuclear myopathy, hypertrophic cardiomyopathy, hypertrophic cardiomyopathy 9, TTN-related myopathy, dilated cardiomyopathy 1G, arrhythmogenic right ventricular cardiomyopathy, myopathy, myofibrillar, 9, with early respiratory failure, familial isolated dilated cardiomyopathy, childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome, autosomal recessive limb-girdle muscular dystrophy type 2J.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE
TTN	NM_001267550.2 linkuse as main transcript	c.3913G>T	p.Gly1305Trp	missense_variant	23/363	ENST00000589042.5
TTN	NM_133379.5 linkuse as main transcript	c.3913G>T	p.Gly1305Trp	missense_variant	23/46	ENST00000360870.10
LOC101927055	NR_120594.1 linkuse as main transcript	n.1830+524C>A		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.3913G>T	p.Gly1305Trp	missense_variant	23/363	5	NM_001267550.2	P1
TTN	ENST00000360870.10 linkuse as main transcript	c.3913G>T	p.Gly1305Trp	missense_variant	23/46	5	NM_133379.5		Q8WZ42-6
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.6182+524C>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152194

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:

0.0000441

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000640

AC:

AN:

250082

Hom.:

AF XY:

0.0000961

AC XY:

AN XY:

135290

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000579

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000925

Gnomad NFE exome

AF:

0.0000975

Gnomad OTH exome

AF:

0.000164

GnomAD4 exome

AF:

0.0000424

AC:

AN:

1461530

Hom.:

Cov.:

AF XY:

0.0000454

AC XY:

AN XY:

727080

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000671

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.0000187

Gnomad4 NFE exome

AF:

0.0000450

Gnomad4 OTH exome

AF:

0.0000828

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152194

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74336

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:

0.0000441

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000225

Hom.:

Bravo

AF:

0.0000227

ExAC

AF:

0.0000741

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.000356

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:9Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:4Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Oct 19, 2016	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Feb 10, 2022	PP3 -
Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Jun 01, 2022	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Jul 22, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Sep 14, 2020	- -

not specified

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Nov 11, 2013	The Gly1305Trp variant in TTN has not been previously reported in individuals wi th cardiomyopathy or in large population studies. Computational analyses (bioche mical amino acid properties, conservation, AlignGVGD, PolyPhen2, and SIFT) sugge st that the Gly1305Trp variant may impact the protein, though this information i s not predictive enough to determine pathogenicity. Additional information is ne eded to fully assess the clinical significance of the Gly1305Trp variant -
Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 03, 2023	Variant summary: TTN c.3913G>T (p.Gly1305Trp) results in a non-conservative amino acid change located in the near Z-disk region of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 6.4e-05 in 250082 control chromosomes (gnomAD). This frequency is not significantly higher than estimated for a pathogenic variant in TTN causing Dilated Cardiomyopathy (6.4e-05 vs 0.00039), allowing no conclusion about variant significance. c.3913G>T has been reported in the literature in at least one individual affected with familial atrial fibrillation (Maltese_2019). This report does 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. The following publication has been ascertained in the context of this evaluation (PMID: 31539150). Six submitters have cited clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as VUS (n=5) or likely benign (n=1). Based on the evidence outlined above, the variant was classified as uncertain significance. -

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 03, 2018

- -

Cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Jul 21, 2016

- -

Cardiovascular phenotype

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 29, 2020

The p.G1259W variant (also known as c.3775G>T), located in coding exon 21 of the TTN gene, results from a G to T substitution at nucleotide position 3775. The glycine at codon 1259 is replaced by tryptophan, an amino acid with highly dissimilar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious 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

Pathogenic

0.98

BayesDel_addAF

Uncertain

0.15

BayesDel_noAF

Pathogenic

0.17

CADD

Uncertain

DANN

Benign

0.96

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

0.97

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

M_CAP

Uncertain

0.23

MetaRNN

Uncertain

0.59

D;D;D;D;D;D;D;D

MetaSVM

Pathogenic

0.91

MutationTaster

Benign

1.0

D;D;D;D;D;D;D

PrimateAI

Uncertain

0.71

PROVEAN

Pathogenic

-6.2

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

REVEL

Pathogenic

0.87

Sift

Pathogenic

0.0

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

Sift4G

Pathogenic

0.0

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

Polyphen

1.0

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

Vest4

0.41

MVP

0.87

MPC

0.50

ClinPred

0.42

GERP RS

5.7

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