2-178785991-C-T

Position:

chr2-178785991-C-T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 3P and 5B. PM5PP2BP4_StrongBP6

The NM_001267550.2(TTN):c.2227G>A(p.Ala743Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000192 in 1,613,890 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/18 in silico tools predict a benign outcome for this variant. 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. A743V) has been classified as Pathogenic.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000020 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:1

Conservation

PhyloP100: -0.0630

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:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -2 ACMG points.

PM5

Other missense variant is known to change same aminoacid residue: Variant chr2-178785990-G-A is described in Lovd as [Pathogenic].

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.

BP4

Computational evidence support a benign effect (MetaRNN=0.03335464).

BP6

Variant 2-178785991-C-T is Benign according to our data. Variant chr2-178785991-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 180564.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=1, Likely_benign=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.2227G>A	p.Ala743Thr	missense_variant	14/363	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5 linkuse as main transcript	c.2227G>A	p.Ala743Thr	missense_variant	14/46	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.2227G>A	p.Ala743Thr	missense_variant	14/363	5	NM_001267550.2	ENSP00000467141	P1
TTN	ENST00000360870.10 linkuse as main transcript	c.2227G>A	p.Ala743Thr	missense_variant	14/46	5	NM_133379.5	ENSP00000354117		Q8WZ42-6

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

152064

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:

0.000193

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000797

AC:

AN:

251060

Hom.:

AF XY:

0.00

AC XY:

AN XY:

135660

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

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:

0.00000882

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000198

AC:

AN:

1461826

Hom.:

Cov.:

AF XY:

0.0000220

AC XY:

AN XY:

727212

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000224

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000252

Gnomad4 SAS exome

AF:

0.0000116

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000216

Gnomad4 OTH exome

AF:

0.0000331

GnomAD4 genome

AF:

0.0000132

AC:

AN:

152064

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74262

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000193

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000151

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000116

AC:

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Revvity Omics, Revvity

May 23, 2023

- -

Primary familial hypertrophic cardiomyopathy

Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Blueprint Genetics

Apr 17, 2014

- -

not specified

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

May 31, 2017

p.Ala743Thr in exon 14 of TTN: This variant is not expected to have clinical sig nificance due to a lack of conservation across species, including >10 mammals. I n addition, computational prediction tools do not suggest a high likelihood of i mpact to the protein. This variant has identified in 2/126354 European chromoso mes by the Genome Aggregation Database (gnomAD; http://gnomad.broadinstitute.org /; dbSNP rs370728359). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.073

BayesDel_addAF

Benign

-0.23

BayesDel_noAF

Benign

-0.48

CADD

Benign

8.9

DANN

Benign

0.73

Eigen

Benign

-1.0

Eigen_PC

Benign

-1.0

FATHMM_MKL

Benign

0.024

LIST_S2

Benign

0.66

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

M_CAP

Benign

0.028

MetaRNN

Benign

0.033

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

MetaSVM

Benign

-1.0

MutationTaster

Benign

1.0

N;N;N;N;N;N;N

PrimateAI

Benign

0.32

PROVEAN

Benign

-0.56

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

REVEL

Benign

0.071

Sift

Benign

0.26

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

Sift4G

Benign

0.19

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

Polyphen

0.0, 0.017

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

Vest4

0.10

MVP

0.067

MPC

0.081

ClinPred

0.076

GERP RS

-1.1

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.030

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