rs727503622

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 1P and 3B. PP2BP4_ModerateBP6

The NM_001267550.2(TTN):c.47978C>A(p.Thr15993Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000595 in 1,612,710 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000062 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:6B:5

Conservation

PhyloP100: 2.49

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:

(HGNC:):

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 -2 ACMG points.

PP2

Missense variant where missense usually causes diseases, TTN

BP4

Computational evidence support a benign effect (MetaRNN=0.10069677).

BP6

Variant 2-178616911-G-T is Benign according to our data. Variant chr2-178616911-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 166024.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Uncertain_significance=6, Benign=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.47978C>A	p.Thr15993Asn	missense_variant	256/363	ENST00000589042.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris
TTN	ENST00000589042.5 linkuse as main transcript	c.47978C>A	p.Thr15993Asn	missense_variant	256/363	5	NM_001267550.2	P1
	ENST00000605334.1 linkuse as main transcript	n.331G>T		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.502+19230G>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.0000395

AC:

AN:

151896

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:

0.000390

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000442

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000485

AC:

AN:

247470

Hom.:

AF XY:

0.0000596

AC XY:

AN XY:

134218

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000280

Gnomad SAS exome

AF:

0.0000327

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000448

Gnomad OTH exome

AF:

0.000166

GnomAD4 exome

AF:

0.0000616

AC:

AN:

1460696

Hom.:

Cov.:

AF XY:

0.0000729

AC XY:

AN XY:

726666

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00177

Gnomad4 SAS exome

AF:

0.0000580

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000990

Gnomad4 OTH exome

AF:

0.0000663

GnomAD4 genome

AF:

0.0000395

AC:

AN:

152014

Hom.:

Cov.:

AF XY:

0.0000538

AC XY:

AN XY:

74302

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000390

Gnomad4 SAS

AF:

0.000208

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000442

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000422

Hom.:

Bravo

AF:

0.0000604

ExAC

AF:

0.0000745

AC:

Asia WGS

AF:

0.00115

AC:

AN:

3476

EpiCase

AF:

0.0000546

EpiControl

AF:

0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:6Benign:5

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:2Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Apr 20, 2015	Missense variants in the TTN gene are considered 'unclassified' if they are not previously reported in the literature and do not have >1% frequency in the population to be considered a polymorphism. Research indicates that truncating mutations in the TTN gene are expected to account for approximately 25% of familial and 18% of sporadic idiopathic DCM; however, truncating variants in the TTN gene have been reported in approximately 3% of reported control alleles. There has been little investigation into non-truncating variants. (Herman D et al. Truncations of titin causing dilated cardiomyopathy. N Eng J Med 366:619-628, 2012) The variant is found in DCM panel(s). -
Likely benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Oct 24, 2018	The p.Thr13425Asn variant in TTN is classified as likely benign because it has b een identified in 0.03% (5/17848) of East Asian chromosomes by gnomAD (http://gn omad.broadinstitute.org). Additionally, computational prediction tools and conse rvation analysis suggest that this variant may not impact the protein ACMG/AMP C riteria applied: BS1, BP4. -
Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	May 16, 2023	Variant summary: TTN c.40274C>A (p.Thr13425Asn) results in a non-conservative amino acid change located in the A band region of the encoded protein sequence. Three of four in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 4.8e-05 in 247470 control chromosomes (gnomAD). This frequency is not significantly higher than estimated for a pathogenic variant in TTN causing Dilated Cardiomyopathy (4.8e-05 vs 0.00039), allowing no conclusion about variant significance. c.40274C>A has been reported in the literature in an individual affected with Neurally mediated syncope, however authors classified the variant as VUS (example: Lee_2022). These report(s) do 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 have been ascertained in the context of this evaluation (PMID: 36005429). Seven clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as VUS and benign/likely benign. Based on the evidence outlined above, the variant was classified as uncertain significance. -

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

Sep 01, 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

not provided

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Revvity Omics, Revvity

Dec 22, 2023

- -

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

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

Tibial muscular dystrophy

Benign:1

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

Cardiovascular phenotype

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 17, 2020

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

Benign

0.12

BayesDel_addAF

Benign

-0.32

BayesDel_noAF

Benign

-0.40

Cadd

Benign

Dann

Benign

0.82

Eigen

Benign

-0.22

Eigen_PC

Benign

-0.13

FATHMM_MKL

Uncertain

0.81

LIST_S2

Benign

0.84

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

M_CAP

Benign

0.034

MetaRNN

Benign

0.10

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

MetaSVM

Benign

-0.70

MutationTaster

Benign

1.0

N;N;N;N;N;N

PrimateAI

Benign

0.30

PROVEAN

Benign

-1.8

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

REVEL

Benign

0.15

Sift

Benign

0.17

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

Polyphen

0.029

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

Vest4

0.37

MutPred

0.45

.;.;.;Loss of phosphorylation at T14352 (P = 0.0506);.;.;Loss of phosphorylation at T14352 (P = 0.0506);

MVP

0.28

MPC

0.11

ClinPred

0.032

GERP RS

0.49

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