2-178590388-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 1P and 1B. PP2BP4

The NM_001267550.2(TTN):c.61337G>A(p.Arg20446His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000332 in 1,596,064 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts 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. R20446C) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000085 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000028 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 7.86

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:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 0 ACMG points.

PP2

Missense variant where missense usually causes diseases, TTN

BP4

Computational evidence support a benign effect (MetaRNN=0.30362684).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.61337G>A	p.Arg20446His	missense_variant	304/363	ENST00000589042.5
TTN-AS1	NR_038272.1 linkuse as main transcript	n.3189-751C>T		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.61337G>A	p.Arg20446His	missense_variant	304/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.417-7208C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.0000855

AC:

AN:

152056

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000169

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.000479

GnomAD3 exomes

AF:

0.0000515

AC:

AN:

233136

Hom.:

AF XY:

0.0000716

AC XY:

AN XY:

125738

show subpopulations

Gnomad AFR exome

AF:

0.000131

Gnomad AMR exome

AF:

0.0000309

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000114

Gnomad SAS exome

AF:

0.0000766

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000374

Gnomad OTH exome

AF:

0.000178

GnomAD4 exome

AF:

0.0000277

AC:

AN:

1444008

Hom.:

Cov.:

AF XY:

0.0000307

AC XY:

AN XY:

716360

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000140

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000253

Gnomad4 SAS exome

AF:

0.0000365

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000254

Gnomad4 OTH exome

AF:

0.0000336

GnomAD4 genome

AF:

0.0000855

AC:

AN:

152056

Hom.:

Cov.:

AF XY:

0.0000808

AC XY:

AN XY:

74254

show subpopulations

Gnomad4 AFR

AF:

0.000169

Gnomad4 AMR

AF:

0.000131

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000294

Gnomad4 OTH

AF:

0.000479

Alfa

AF:

0.0000987

Hom.:

Bravo

AF:

0.0000982

ESP6500AA

AF:

0.000262

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000497

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 12, 2017

- -

Cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Apr 23, 2021

- -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Revvity Omics, Revvity

May 13, 2019

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.59

BayesDel_addAF

Benign

-0.060

BayesDel_noAF

Benign

-0.090

Cadd

Uncertain

Dann

Benign

0.90

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.97

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

M_CAP

Benign

0.015

MetaRNN

Benign

0.30

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

MetaSVM

Uncertain

0.069

MutationTaster

Benign

1.0

D;D;D;D;D;D

PrimateAI

Uncertain

0.70

PROVEAN

Uncertain

-4.0

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

REVEL

Uncertain

0.55

Sift

Uncertain

0.0020

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

Polyphen

1.0

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

Vest4

0.38

MVP

0.48

MPC

0.52

ClinPred

0.29

GERP RS

6.1

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