2-178678505-G-A

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4_StrongBP6

The NM_001267550.2(TTN):c.33827-8C>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000873 in 1,557,040 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.00046 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000047 ( 0 hom. )

Consequence

TTN
NM_001267550.2 splice_region, intron

Scores

Splicing: ADA: 0.00003670

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:5

Conservation

PhyloP100: -0.550

Publications

0 publications found

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:

LOC124906100 (HGNC:):

LOC124906100 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -5 ACMG points.

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.57).

BP6

Variant 2-178678505-G-A is Benign according to our data. Variant chr2-178678505-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 46893.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein
TTN	NM_001267550.2	MANE Select	c.33827-8C>T	splice_region intron	N/A	NP_001254479.2
TTN	NM_001256850.1		c.32876-8C>T	splice_region intron	N/A	NP_001243779.1
TTN	NM_133378.4		c.30095-8C>T	splice_region intron	N/A	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.33827-8C>T	splice_region intron	N/A	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.33827-8C>T	splice_region intron	N/A	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.33551-8C>T	splice_region intron	N/A	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.000455

AC:

AN:

151814

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00155

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

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:

0.0000442

Gnomad OTH

AF:

0.000961

GnomAD2 exomes

AF:

0.000122

AC:

AN:

172808

AF XY:

0.000108

show subpopulations

Gnomad AFR exome

AF:

0.00167

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000841

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000129

Gnomad OTH exome

AF:

0.000225

GnomAD4 exome

AF:

0.0000470

AC:

AN:

1405108

Hom.:

Cov.:

AF XY:

0.0000417

AC XY:

AN XY:

694972

show subpopulations

African (AFR)

AF:

0.00132

AC:

AN:

31128

American (AMR)

AF:

0.00

AC:

AN:

32960

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

24822

East Asian (EAS)

AF:

0.00

AC:

AN:

37536

South Asian (SAS)

AF:

0.0000532

AC:

AN:

75188

European-Finnish (FIN)

AF:

0.0000778

AC:

AN:

51434

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5664

European-Non Finnish (NFE)

AF:

0.0000129

AC:

AN:

1088130

Other (OTH)

AF:

0.0000515

AC:

AN:

58246

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.470

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.000461

AC:

AN:

151932

Hom.:

Cov.:

AF XY:

0.000498

AC XY:

AN XY:

74266

show subpopulations

African (AFR)

AF:

0.00157

AC:

AN:

41494

American (AMR)

AF:

0.00

AC:

AN:

15218

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3460

East Asian (EAS)

AF:

0.00

AC:

AN:

5166

South Asian (SAS)

AF:

0.00

AC:

AN:

4820

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10574

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000442

AC:

AN:

67890

Other (OTH)

AF:

0.000951

AC:

AN:

2104

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.511

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.000181

Hom.:

Bravo

AF:

0.000480

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:5

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:1Benign:2

Jan 24, 2012

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant classified as Uncertain Significance - Favor Benign. The 30095-8C>T vari ant (TTN) has been identified in 0.1% (4/2944) of African American chromosomes b y the NHLBI Exome Sequencing Project in a broad population (http://evs.gs.washin gton.edu/EVS). This variant is located in the 3' splice region and computational tools do not predict altered splicing, though this information is not predictiv e enough to rule out pathogenicity. Although this data suggests that the 30095-8 C>T variant may be benign, additional information is needed to fully assess its clinical significance.

Apr 13, 2016

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.

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

BS1;BP6

not provided

Uncertain:1

Dec 28, 2015

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

TTN-related disorder

Benign:1

Sep 27, 2023

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 06, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Cardiomyopathy

Benign:1

Dec 11, 2020

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

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.57

CADD

Benign

(source)

DANN

Benign

0.72

PhyloP100

-0.55

Mutation Taster

=100/0

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Benign

0.000037

dbscSNV1_RF

Benign

0.010

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over