2-178615707-G-A

Position:

chr2-178615707-G-A

Variant summary

Our verdict is Benign. Variant got -12 ACMG points: 1P and 13B. PP2BP4_StrongBP6BS1BS2

The NM_001267550.2(TTN):c.48394C>T(p.Arg16132Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000315 in 1,612,356 control chromosomes in the GnomAD database, including 5 homozygotes. 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R16132H) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00024 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00032 ( 5 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

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

Conservation

PhyloP100: 1.23

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 Benign. Variant got -12 ACMG points.

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=0.010625243).

BP6

Variant 2-178615707-G-A is Benign according to our data. Variant chr2-178615707-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 202664.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Uncertain_significance=6, Benign=2}. Variant chr2-178615707-G-A is described in Lovd as [Likely_benign].

BS1

Variant frequency is greater than expected in population eas. gnomad4 allele frequency = 0.000243 (37/151960) while in subpopulation EAS AF= 0.00605 (31/5120). AF 95% confidence interval is 0.00438. There are 0 homozygotes in gnomad4. There are 16 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.

BS2

High Homozygotes in GnomAdExome4 at 5 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.48394C>T	p.Arg16132Cys	missense_variant	258/363	ENST00000589042.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.48394C>T	p.Arg16132Cys	missense_variant	258/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.502+18026G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.000244

AC:

AN:

151842

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:

0.00604

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.0000943

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000295

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000157

AC:

AN:

248222

Hom.:

AF XY:

0.000134

AC XY:

AN XY:

134652

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00179

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000464

Gnomad NFE exome

AF:

0.00000890

Gnomad OTH exome

AF:

0.000664

GnomAD4 exome

AF:

0.000323

AC:

471

AN:

1460396

Hom.:

Cov.:

AF XY:

0.000334

AC XY:

243

AN XY:

726516

show subpopulations

Gnomad4 AFR exome

AF:

0.0000300

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0114

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.0000936

Gnomad4 NFE exome

AF:

0.00000360

Gnomad4 OTH exome

AF:

0.000133

GnomAD4 genome

AF:

0.000243

AC:

AN:

151960

Hom.:

Cov.:

AF XY:

0.000215

AC XY:

AN XY:

74264

show subpopulations

Gnomad4 AFR

AF:

0.0000723

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00605

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.0000943

Gnomad4 NFE

AF:

0.0000295

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000111

Hom.:

Bravo

AF:

0.000121

ExAC

AF:

0.000116

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3476

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:6Benign:5

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:2Benign:1

Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Apr 18, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	May 21, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Apr 27, 2018	- -

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. -

Dilated cardiomyopathy 1G

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

Cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Nov 05, 2015

- -

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

not specified

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

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

May 16, 2023

Variant summary: TTN c.40690C>T (p.Arg13564Cys) results in a non-conservative amino acid change located in the A-band of the encoded protein sequence. Two of four in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00016 in 248222 control chromosomes, predominantly at a frequency of 0.0018 within the East Asian subpopulation in the gnomAD database. The observed variant frequency within East Asian control individuals in the gnomAD database is approximately 5 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Dilated Cardiomyopathy phenotype (0.00039), strongly suggesting that the variant is a benign polymorphism found primarily in populations of East Asian origin. c.40690C>T has been reported in the literature in individuals affected with myocyte disarray or preeclampsia (Gammill_2018, Hata_2019). These report 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 publications have been ascertained in the context of this evaluation (PMID: 30021846, 30959811). Seven ClinVar submitter (evaluation after 2014) cites this variant as uncertain significance (n=4), likely benign (n=2) and benign (n=1). Based on the evidence outlined above, the variant was classified as likely benign. -

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

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 29, 2024

- -

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. -

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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.13

BayesDel_addAF

Benign

-0.45

BayesDel_noAF

Benign

-0.43

CADD

Benign

DANN

Benign

0.84

Eigen

Benign

-0.49

Eigen_PC

Benign

-0.31

FATHMM_MKL

Benign

0.69

LIST_S2

Uncertain

0.91

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

M_CAP

Benign

0.0078

MetaRNN

Benign

0.011

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

MetaSVM

Benign

-1.1

MutationAssessor

Benign

-0.23

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

MutationTaster

Benign

0.96

D;D;D;D;D;D

PrimateAI

Benign

0.27

PROVEAN

Benign

-2.2

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

REVEL

Benign

0.11

Sift

Benign

0.11

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

Polyphen

0.0

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

Vest4

0.19

MVP

0.32

MPC

0.11

ClinPred

0.053

GERP RS

0.98

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