rs56307213

chr2-178566349-C-G

Variant summary

Our verdict is Benign. Variant got -19 ACMG points: 1P and 20B. PP2 BP4_Strong BP6_Very_Strong BS1 BS2

The NM_001267550.2(TTN):c.79783G>C(p.Asp26595His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0176 in 1,613,520 control chromosomes in the GnomAD database, including 304 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Synonymous variant affecting the same amino acid position (i.e. D26595D) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.014 (22 hom., cov: 33)
  • Exomes 𝑓: 0.018 (282 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:25
• Conservation: PhyloP100: 7.86

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-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]

ACMG classification

Verdict is Benign. Variant got -19 ACMG points.

• PP2: Missense variant where missense usually causes diseases, TTN
• BP4: Computational evidence support a benign effect (MetaRNN=0.008546919).
• BP6: Variant 2-178566349-C-G is Benign according to our data. Variant chr2-178566349-C-G is described in ClinVar as [Likely_benign]. Clinvar id is 47380.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178566349-C-G is described in Lovd as [Benign]. Variant chr2-178566349-C-G is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population nfe. gnomad4 allele frequency = 0.0144 (2195/152162) while in subpopulation NFE AF= 0.0213 (1449/67982). AF 95% confidence interval is 0.0204. There are 22 homozygotes in gnomad4. There are 1060 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 22 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.79783G>C	p.Asp26595His	missense_variant	326/363	ENST00000589042.5
TTN-AS1	NR_038272.1	n.2044-16223C>G		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.79783G>C	p.Asp26595His	missense_variant	326/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.417-31247C>G		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.0144 AC: 2197 AN: 152044 Hom.: 22 Cov.: 33

Gnomad AFR AF: 0.00418

Gnomad AMI AF: 0.00329

Gnomad AMR AF: 0.0146

Gnomad ASJ AF: 0.0104

Gnomad EAS AF: 0.000387

Gnomad SAS AF: 0.0112

Gnomad FIN AF: 0.0216

Gnomad MID AF: 0.00949

Gnomad NFE AF: 0.0213

Gnomad OTH AF: 0.0120

GnomAD3 exomes AF: 0.0146 AC: 3638 AN: 248720 Hom.: 29 AF XY: 0.0148 AC XY: 1992 AN XY: 134926

Gnomad AFR exome AF: 0.00349

Gnomad AMR exome AF: 0.0102

Gnomad ASJ exome AF: 0.00865

Gnomad EAS exome AF: 0.0000557

Gnomad SAS exome AF: 0.0109

Gnomad FIN exome AF: 0.0222

Gnomad NFE exome AF: 0.0198

Gnomad OTH exome AF: 0.0171

GnomAD4 exome AF: 0.0179 AC: 26133 AN: 1461358 Hom.: 282 Cov.: 38 AF XY: 0.0178 AC XY: 12933 AN XY: 726970

Gnomad4 AFR exome AF: 0.00311

Gnomad4 AMR exome AF: 0.0110

Gnomad4 ASJ exome AF: 0.00907

Gnomad4 EAS exome AF: 0.0000504

Gnomad4 SAS exome AF: 0.0111

Gnomad4 FIN exome AF: 0.0240

Gnomad4 NFE exome AF: 0.0198

Gnomad4 OTH exome AF: 0.0162

GnomAD4 genome AF: 0.0144 AC: 2195 AN: 152162 Hom.: 22 Cov.: 33 AF XY: 0.0143 AC XY: 1060 AN XY: 74366

Gnomad4 AFR AF: 0.00416

Gnomad4 AMR AF: 0.0146

Gnomad4 ASJ AF: 0.0104

Gnomad4 EAS AF: 0.000388

Gnomad4 SAS AF: 0.0112

Gnomad4 FIN AF: 0.0216

Gnomad4 NFE AF: 0.0213

Gnomad4 OTH AF: 0.0118

Alfa AF: 0.0171 Hom.: 26

Bravo AF: 0.0128

TwinsUK AF: 0.0167 AC: 62

ALSPAC AF: 0.0187 AC: 72

ESP6500AA AF: 0.00469 AC: 19

ESP6500EA AF: 0.0200 AC: 168

ExAC AF: 0.0147 AC: 1784

Asia WGS AF: 0.00549 AC: 19 AN: 3478

EpiCase AF: 0.0205

EpiControl AF: 0.0211

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:25

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:9

Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Likely benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 21, 2021	- -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Mar 26, 2012	Asp24027His in exon 275 of TTN: This variant is classified as benign based on it s high frequency in the general population (dbSNP rs56307213; NHLBI Exome Sequen cing Project, http://evs.gs.washington.edu/EVS). -
Benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Aug 15, 2013	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Oct 30, 2013	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Benign, criteria provided, single submitter	research	Biesecker Lab/Clinical Genomics Section, National Institutes of Health	Jun 24, 2013	- -
Benign, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Benign, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -

not provided Benign:4

Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	May 06, 2019	- -
Likely benign, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -
Benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Oct 23, 2023	- -
Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -

Autosomal recessive limb-girdle muscular dystrophy type 2J Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Early-onset myopathy with fatal cardiomyopathy Benign:2

Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

Tibial muscular dystrophy Benign:2

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. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

Myopathy, myofibrillar, 9, with early respiratory failure Benign:2

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. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

TTN-related disorder Benign:1

Benign, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Apr 08, 2019

This variant is classified as benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

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

Benign, criteria provided, single submitter

clinical testing

Invitae

Feb 01, 2024

- -

Dilated cardiomyopathy 1G Benign:1

Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Cardiovascular phenotype Benign:1

Benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 27, 2013

This alteration is classified as benign based on a combination of the following: 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	Pathogenic	0.78
BayesDel_addAF	Benign	-0.23	T
BayesDel_noAF	Benign	-0.090
Cadd	Benign	22
Dann	Benign	0.87
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.97
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;D;.;D;D;D
MetaRNN	Benign	0.0085	T;T;T;T;T;T;T
MetaSVM	Uncertain	0.12	D
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.71	T
PROVEAN	Pathogenic	-5.1	D;D;.;.;D;D;.
REVEL	Pathogenic	0.69
Sift	Uncertain	0.0070	D;D;.;.;D;D;.
Polyphen		1.0	.;.;.;D;.;.;D
Vest4		0.34
MPC		0.50
ClinPred		0.046	T
GERP RS		5.9

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

Other links and lift over

dbSNP: rs56307213; hg19: chr2-179431076;