2-178785999-C-T

Variant names:

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM5BP4_Strong

The NM_001267550.2(TTN):c.2219G>A(p.Arg740His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000136 in 1,613,950 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R740L) has been classified as Pathogenic.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000013 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 0.627

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 chr2-178785999-C-A is described in Lovd as [Pathogenic].

BP4

Computational evidence support a benign effect (MetaRNN=0.025882423).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.2219G>A	p.Arg740His	missense_variant	Exon 14 of 363	ENST00000589042.5	NP_001254479.2	A0A0A0MTS7
TTN	NM_133379.5 link	c.2219G>A	p.Arg740His	missense_variant	Exon 14 of 46	ENST00000360870.10	NP_596870.2	Q8WZ42-6Q7Z3B7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.2219G>A	p.Arg740His	missense_variant	Exon 14 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7
TTN	ENST00000360870.10 link	c.2219G>A	p.Arg740His	missense_variant	Exon 14 of 46	5	NM_133379.5	ENSP00000354117.4		Q8WZ42-6

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152130

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000725

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000199

AC:

AN:

251002

Hom.:

AF XY:

0.0000295

AC XY:

AN XY:

135634

show subpopulations

Gnomad AFR exome

AF:

0.0000615

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000653

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000130

AC:

AN:

1461820

Hom.:

Cov.:

AF XY:

0.0000110

AC XY:

AN XY:

727210

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000580

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000117

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152130

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74320

show subpopulations

Gnomad4 AFR

AF:

0.0000725

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:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000648

Hom.:

Bravo

AF:

0.0000302

ExAC

AF:

0.0000247

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Aug 26, 2019

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: TTN c.2219G>A (p.Arg740His) results in a non-conservative amino acid change located in the Z-disk region of the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 2e-05 in 251002 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.2219G>A in individuals affected with Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Co-occurrence with another likely pathogenic variant in the TTN gene has been observed at our laboratory (TTN c.34782_34785delTTGT, p.Cys11595fs*9), providing supporting evidence for a benign role. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.057

BayesDel_addAF

Benign

-0.36

BayesDel_noAF

Benign

-0.58

CADD

Benign

DANN

Benign

0.59

Eigen

Benign

-1.2

Eigen_PC

Benign

-1.1

FATHMM_MKL

Benign

0.015

LIST_S2

Benign

0.71

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

M_CAP

Benign

0.030

MetaRNN

Benign

0.026

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

MetaSVM

Benign

-1.0

PrimateAI

Benign

0.21

PROVEAN

Benign

1.8

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

REVEL

Benign

0.11

Sift

Benign

0.70

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

Sift4G

Benign

0.89

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

Polyphen

0.0

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

Vest4

0.042

MVP

0.040

MPC

0.10

ClinPred

0.023

GERP RS

1.2

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