NM_001267550.2:c.1066G>C

Variant names:

• chr2-178795101-C-G
• rs144531477
• NM_001267550.2:c.1066G>C

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_001267550.2(TTN):​c.1066G>C​(p.Glu356Gln) variant causes a missense change. The variant allele was found at a frequency of 0.000136 in 1,613,992 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/19 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. E356K) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.00012 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00014 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:11 B:3 O:1
• Conservation: PhyloP100: 6.43
• Publications: 4 publications found

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 Gene-Disease associations (from GenCC):

• dilated cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• dilated cardiomyopathy 1G

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• early-onset myopathy with fatal cardiomyopathy

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, G2P
• TTN-related myopathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• myopathy, myofibrillar, 9, with early respiratory failure

  Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, ClinGen, Ambry Genetics
• tibial muscular dystrophy

  Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen, Orphanet
• autosomal recessive limb-girdle muscular dystrophy type 2J

  Inheritance: AR Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
• hypertrophic cardiomyopathy 9

  Inheritance: AD Classification: MODERATE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), PanelApp Australia
• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• autosomal recessive centronuclear myopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• congenital myopathy

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• hereditary skeletal muscle disorder

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• hypertrophic cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.1143195).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.1066G>C	p.Glu356Gln	missense_variant	Exon 7 of 363	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.1066G>C	p.Glu356Gln	missense_variant	Exon 7 of 46	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.1066G>C	p.Glu356Gln	missense_variant	Exon 7 of 363	5	NM_001267550.2	ENSP00000467141.1
TTN	ENST00000360870.10	c.1066G>C	p.Glu356Gln	missense_variant	Exon 7 of 46	5	NM_133379.5	ENSP00000354117.4

Frequencies

GnomAD3 genomes AF: 0.000118 AC: 18 AN: 152220 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000482

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000589

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: 0.000103

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000155 AC: 39 AN: 251140 AF XY: 0.000177

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.000607

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000123

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.000138 AC: 201 AN: 1461772 Hom.: 0 Cov.: 32 AF XY: 0.000133 AC XY: 97 AN XY: 727182

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.000648 AC: 29 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39686

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53340

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.000148 AC: 165 AN: 1111986

Other (OTH) AF: 0.0000993 AC: 6 AN: 60394

GnomAD4 genome AF: 0.000118 AC: 18 AN: 152220 Hom.: 0 Cov.: 33 AF XY: 0.000161 AC XY: 12 AN XY: 74356

African (AFR) AF: 0.0000482 AC: 2 AN: 41462

American (AMR) AF: 0.000589 AC: 9 AN: 15284

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5200

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10622

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.000103 AC: 7 AN: 68036

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.0000722 Hom.: 0

Bravo AF: 0.000166

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000233 AC: 2

ExAC AF: 0.000115 AC: 14

EpiCase AF: 0.0000545

EpiControl AF: 0.000178

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:11 Benign:3 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:3 Other:1

Jul 03, 2017

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 14, 2023

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 09, 2013

GeneDx

Significance: not provided

Review Status: no classification provided

Collection Method: clinical testing

- -

Dec 12, 2019

Mayo Clinic Laboratories, Mayo Clinic

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified Uncertain:2 Benign:1

Jul 29, 2015

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Glu356Gln variant in TTN has not been previously reported in individuals w ith cardiomyopathy, but has been identified in 8/66726 European chromosomes and 5/11572 Latino chromosomes by the Exome Aggregation Consortium (ExAC, http://exa c.broadinstitute.org; dbSNP rs144531477). Computational prediction tools and con servation analysis suggest that this variant may impact the protein, though this information is not predictive enough to determine pathogenicity. In summary, th e clinical significance of the p.Glu356Gln variant is uncertain. -

May 23, 2019

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The TTN c.1066G>C; p.Glu356Gln variant (rs144531477; ClinVar Variation ID: 202582) is rare in the general population (<1% allele frequency in the Genome Aggregation Database) and has not been reported in the medical literature in association with dilated cardiomyopathy (DCM) or other TTN-related disease. The clinical relevance of rare missense variants in this gene, which are identified on average once per individual sequenced in affected populations (Herman 2012), is not well understood. Yet, evidence suggests that the vast majority of such missense variants do not contribute to the clinical outcome of DCM (Begay 2015). Thus, the clinical significance of the p.Glu356Gln variant cannot be determined with certainty. References: Begay RL et al. Role of Titin Missense Variants in Dilated Cardiomyopathy. J Am Heart Assoc. 2015 Nov 13;4(11). Herman DS et al. Truncations of titin causing dilated cardiomyopathy. N Engl J Med. 2012 Feb 16;366(7):619-28. Linke and Hamdani. Gigantic business: titin properties and function through thick and thin. Circ Res 2014; 114(6): 1052-1068. -

Apr 09, 2025

Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Autosomal recessive limb-girdle muscular dystrophy type 2J Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. -

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

May 20, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dilated cardiomyopathy 1G Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. -

Early-onset myopathy with fatal cardiomyopathy Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. -

Arthrogryposis syndrome Uncertain:1

Mar 27, 2020

Cambridge Genomics Laboratory, East Genomic Laboratory Hub, NHS Genomic Medicine Service

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiovascular phenotype Uncertain:1

Aug 26, 2018

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.E356Q variant (also known as c.1066G>C), located in coding exon 6 of the TTN gene, results from a G to C substitution at nucleotide position 1066. The glutamic acid at codon 356 is replaced by glutamine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Tibial muscular dystrophy Benign:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Benign	-0.22	T
BayesDel_noAF	Benign	-0.19
CADD	Benign	23
DANN	Uncertain	0.98
Eigen	Uncertain	0.64
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.82	T;T;T;.;T;T;T;T
M_CAP	Benign	0.025	D
MetaRNN	Benign	0.11	T;T;T;T;T;T;T;T
MetaSVM	Uncertain	-0.19	T
PhyloP100		6.4
PrimateAI	Uncertain	0.52	T
PROVEAN	Benign	-1.6	N;N;.;.;N;N;.;N
REVEL	Benign	0.18
Sift	Benign	0.18	T;T;.;.;T;T;.;D
Sift4G	Uncertain	0.055	.;.;.;.;.;.;.;T
Polyphen		0.96, 1.0	.;.;.;D;.;.;D;D
Vest4		0.21
MVP		0.33
MPC		0.26
ClinPred		0.037	T
GERP RS		6.1
PromoterAI		-0.0046	Neutral
Mutation Taster		=83/17	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs144531477; hg19: chr2-179659828;