2-178799714-A-G

Variant names:

• chr2-178799714-A-G
• rs376527094
• NM_001267550.2:c.687T>C

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Moderate BP6 BP7

The NM_001267550.2(TTN):​c.687T>C​(p.Phe229Phe) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00026 in 1,614,210 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 Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00017 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00027 (0 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:6 B:14
• Conservation: PhyloP100: 2.83
• Publications: 5 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 -4 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.45).
• BP6: Variant 2-178799714-A-G is Benign according to our data. Variant chr2-178799714-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 178277.
• BP7: Synonymous conserved (PhyloP=2.83 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.687T>C	p.Phe229Phe	synonymous_variant	Exon 6 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.687T>C	p.Phe229Phe	synonymous_variant	Exon 6 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.000171 AC: 26 AN: 152244 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000262

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: 0.000279

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000183 AC: 46 AN: 251100 AF XY: 0.000221

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000260

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000300

Gnomad OTH exome AF: 0.000490

GnomAD4 exome AF: 0.000269 AC: 393 AN: 1461848 Hom.: 0 Cov.: 31 AF XY: 0.000272 AC XY: 198 AN XY: 727234

African (AFR) AF: 0.0000597 AC: 2 AN: 33480

American (AMR) AF: 0.000313 AC: 14 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: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53412

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

European-Non Finnish (NFE) AF: 0.000327 AC: 364 AN: 1111990

Other (OTH) AF: 0.000199 AC: 12 AN: 60394

GnomAD4 genome AF: 0.000171 AC: 26 AN: 152362 Hom.: 0 Cov.: 32 AF XY: 0.000161 AC XY: 12 AN XY: 74512

African (AFR) AF: 0.0000722 AC: 3 AN: 41580

American (AMR) AF: 0.000261 AC: 4 AN: 15302

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5188

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10628

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.000279 AC: 19 AN: 68042

Other (OTH) AF: 0.00 AC: 0 AN: 2116

Alfa AF: 0.000384 Hom.: 0

Bravo AF: 0.000193

EpiCase AF: 0.000327

EpiControl AF: 0.000178

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:6 Benign:14

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:7

-

Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Aug 14, 2019

Athena Diagnostics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 05, 2016

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

-

Genome Diagnostics Laboratory, University Medical Center Utrecht

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

-

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

-

Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

-

Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Aug 22, 2023

Revvity Omics, Revvity

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified Benign:4

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

BP6;BP7 -

May 02, 2022

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

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jul 21, 2017

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

p.Phe229Phe in exon 6 of TTN: This variant is not expected to have clinical sign ificance because it does not alter an amino acid residue and is not located with in the splice consensus sequence. It has been identified in 49/276838 chromosome s by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs376527094). -

Oct 02, 2014

GeneDx

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. -

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

Jan 15, 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. -

Dilated cardiomyopathy 1G Uncertain:1

Jan 15, 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 15, 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. -

Tibial muscular dystrophy Uncertain:1

Jan 15, 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. -

Myopathy, myofibrillar, 9, with early respiratory failure Uncertain:1

Jan 15, 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. -

TTN-related disorder Benign:1

Nov 27, 2019

PreventionGenetics, part of Exact Sciences

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

This variant is classified as likely 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

Jan 22, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiovascular phenotype Benign:1

Feb 02, 2021

Ambry Genetics

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as 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
BayesDel_noAF	Benign	-0.45
CADD	Benign	13
DANN	Benign	0.74
PhyloP100		2.8
Mutation Taster		=82/18	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: rs376527094; hg19: chr2-179664441; COSMIC: COSV104643473;