rs202125813

Variant summary

Our verdict is Benign. Variant got -15 ACMG points: 1P and 16B. PP2BP4_StrongBP6_Very_StrongBS1

The NM_001267550.2(TTN):c.66977A>G(p.Lys22326Arg) variant causes a missense change. The variant allele was found at a frequency of 0.000302 in 1,613,306 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. 13/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K22326E) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0016 ( 1 hom., cov: 33)

Exomes 𝑓: 0.00016 ( 1 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Benign/Likely benign criteria provided, multiple submitters, no conflicts B:15

Conservation

PhyloP100: 3.89

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:

(HGNC:):

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 -15 ACMG points.

PP2

Missense variant where missense usually causes diseases, TTN

BP4

Computational evidence support a benign effect (MetaRNN=0.006349772).

BP6

Variant 2-178580402-T-C is Benign according to our data. Variant chr2-178580402-T-C is described in ClinVar as [Likely_benign]. Clinvar id is 47245.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178580402-T-C is described in Lovd as [Benign]. Variant chr2-178580402-T-C is described in Lovd as [Likely_benign].

BS1

Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00163 (248/152220) while in subpopulation AFR AF= 0.00565 (235/41584). AF 95% confidence interval is 0.00506. There are 1 homozygotes in gnomad4. There are 123 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.66977A>G	p.Lys22326Arg	missense_variant	317/363	ENST00000589042.5
TTN-AS1	NR_038272.1 linkuse as main transcript	n.2044-2170T>C		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris
TTN	ENST00000589042.5 linkuse as main transcript	c.66977A>G	p.Lys22326Arg	missense_variant	317/363	5	NM_001267550.2	P1
	ENST00000603521.1 linkuse as main transcript	n.1613T>C		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.417-17194T>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.00163

AC:

248

AN:

152102

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00567

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000721

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:

0.0000147

Gnomad OTH

AF:

0.000478

GnomAD3 exomes

AF:

0.000367

AC:

AN:

248274

Hom.:

AF XY:

0.000245

AC XY:

AN XY:

134684

show subpopulations

Gnomad AFR exome

AF:

0.00517

Gnomad AMR exome

AF:

0.000261

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:

0.00000891

Gnomad OTH exome

AF:

0.000166

GnomAD4 exome

AF:

0.000164

AC:

239

AN:

1461086

Hom.:

Cov.:

AF XY:

0.000116

AC XY:

AN XY:

726842

show subpopulations

Gnomad4 AFR exome

AF:

0.00583

Gnomad4 AMR exome

AF:

0.000335

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000900

Gnomad4 OTH exome

AF:

0.000298

GnomAD4 genome

AF:

0.00163

AC:

248

AN:

152220

Hom.:

Cov.:

AF XY:

0.00165

AC XY:

123

AN XY:

74400

show subpopulations

Gnomad4 AFR

AF:

0.00565

Gnomad4 AMR

AF:

0.000720

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.000473

Alfa

AF:

0.000315

Hom.:

Bravo

AF:

0.00189

ESP6500AA

AF:

0.00375

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.000406

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:15

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Benign:5

Likely benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Nov 12, 2015	- -
Likely benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Apr 10, 2012	Lys19758Arg in exon 266 of TTN: This variant is not expected to have clinical si gnificance because it has been identified in 0.4% (12/3048) of African American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http: //evs.gs.washington.edu/EVS). Lys19758Arg in exon 266 of TTN (allele frequenc y = 0.4%, 12/3048) ** -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Nov 29, 2021	Variant summary: TTN c.59273A>G (p.Lys19758Arg) results in a conservative amino acid change located in the A-band 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 0.00049 in 279656 control chromosomes, predominantly at a frequency of 0.0053 within the African or African-American subpopulation in the gnomAD database, including 2 homozygotes. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 13.5-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 African or African-American origin. c.59273A>G has been reported in the literature in an African American individual affected with Dilated Cardiomyopathy (Pugh_2014). This report does 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. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as benign (n=2) / likely benign (n=2). Based on the evidence outlined above, the variant was classified as benign. -
Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Feb 19, 2020	- -

not provided

Benign:4

Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Likely benign, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Sep 18, 2020	- -
Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Dec 01, 2023	TTN: BP4, BS2 -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Benign:1

Benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Sep 10, 2021

- -

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

Benign:1

Benign, criteria provided, single submitter

clinical testing

Invitae

Jan 20, 2024

- -

Early-onset myopathy with fatal cardiomyopathy

Benign:1

Benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Sep 10, 2021

- -

Tibial muscular dystrophy

Benign:1

Benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Sep 10, 2021

- -

Myopathy, myofibrillar, 9, with early respiratory failure

Benign:1

Benign, criteria provided, single submitter

clinical testing

Genome-Nilou Lab

Sep 10, 2021

- -

Cardiovascular phenotype

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 14, 2018

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.074

BayesDel_addAF

Benign

-0.51

BayesDel_noAF

Benign

-0.50

Cadd

Benign

Dann

Benign

0.85

Eigen

Benign

-0.45

Eigen_PC

Benign

-0.20

FATHMM_MKL

Benign

0.74

LIST_S2

Uncertain

0.90

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

M_CAP

Benign

0.0099

MetaRNN

Benign

0.0063

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

MetaSVM

Benign

-1.1

MutationTaster

Benign

0.78

D;D;D;D;D;D

PrimateAI

Uncertain

0.54

PROVEAN

Benign

-1.1

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

REVEL

Benign

0.055

Sift

Benign

0.89

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

Polyphen

0.0060

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

Vest4

0.32

MVP

0.11

MPC

0.071

ClinPred

0.014

GERP RS

4.2

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.050

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