Genetic Variant TTN:p.Met8504Val (chr2-178717224-T-C) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001267550.2(TTN):c.25510A>G(p.Met8504Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000124 in 1,613,676 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. M8504L) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 5.12

Publications

0 publications found

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:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.25510A>G	p.Met8504Val	missense_variant	Exon 88 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.25510A>G	p.Met8504Val	missense_variant	Exon 88 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461384

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726984

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33448

American (AMR)

AF:

0.00

AC:

AN:

44718

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26120

East Asian (EAS)

AF:

0.00

AC:

AN:

39692

South Asian (SAS)

AF:

0.00

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53374

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

9.00e-7

AC:

AN:

1111662

Other (OTH)

AF:

0.00

AC:

AN:

60348

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152292

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74460

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41574

American (AMR)

AF:

0.0000654

AC:

AN:

15288

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5184

South Asian (SAS)

AF:

0.00

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68010

Other (OTH)

AF:

0.00

AC:

AN:

2116

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.16

BayesDel_addAF

Benign

-0.019

BayesDel_noAF

Benign

-0.27

CADD

Uncertain

(source)

DANN

Benign

0.91

Eigen

Benign

-0.093

Eigen_PC

Benign

0.13

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.81

T;T;.;T

M_CAP

Benign

0.015

MetaRNN

Benign

0.18

T;T;T;T

MetaSVM

Benign

-0.93

PhyloP100

5.1

PrimateAI

Uncertain

0.57

PROVEAN

Benign

-2.0

N;.;.;.

REVEL

Benign

0.20

Sift

Benign

0.15

T;.;.;.

Polyphen

0.073

.;.;B;B

Vest4

0.34

MutPred

0.49

.;.;Loss of ubiquitination at K8186 (P = 0.073);Loss of ubiquitination at K8186 (P = 0.073);

MVP

0.44

MPC

0.089

ClinPred

0.26

GERP RS

5.5

Mutation Taster

=72/28

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.39

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.39

Position offset: 1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over