chr2-178569330-G-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):c.76802C>A(p.Thr25601Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,613,138 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T25601M) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000034 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 9.94

Publications

2 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:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.2810543).

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	HGVSp	Effect	Exon Rank	Protein
TTN	NM_001267550.2	MANE Select	c.76802C>A	p.Thr25601Lys	missense	Exon 326 of 363	NP_001254479.2
TTN	NM_001256850.1		c.71879C>A	p.Thr23960Lys	missense	Exon 276 of 313	NP_001243779.1
TTN	NM_133378.4		c.69098C>A	p.Thr23033Lys	missense	Exon 275 of 312	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.76802C>A	p.Thr25601Lys	missense	Exon 326 of 363	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.76646C>A	p.Thr25549Lys	missense	Exon 324 of 361	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.76526C>A	p.Thr25509Lys	missense	Exon 324 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

152086

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000403

AC:

AN:

248204

AF XY:

0.00000743

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000342

AC:

AN:

1461052

Hom.:

Cov.:

AF XY:

0.00000550

AC XY:

AN XY:

726800

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33436

American (AMR)

AF:

0.00

AC:

AN:

44694

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26106

East Asian (EAS)

AF:

0.00

AC:

AN:

39682

South Asian (SAS)

AF:

0.0000348

AC:

AN:

86144

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53376

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5752

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111510

Other (OTH)

AF:

0.0000166

AC:

AN:

60352

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

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:

0.00000658

AC:

AN:

152086

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74282

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41444

American (AMR)

AF:

0.00

AC:

AN:

15246

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5172

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

67982

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ExAC

AF:

0.00000828

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Dilated cardiomyopathy 1G

Uncertain:1

Feb 02, 2022

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as VUS-3B. Following criteria are met: 0102 - Loss of function is known mechanism of disease in this gene. In addition, dominant-negative is also a suggested mechanism. (PMID: 25589632). (I) 0108 - This gene is associated with both recessive and dominant disease (OMIM). (I) 0112 - The condition associated with this gene has incomplete penetrance. Variants in this gene that result in a premature truncating codon (PTC) are known to have reduced penetrance in DCM (PMID: 25589632). (I) 0200 - Variant is predicted to result in a missense amino acid change from threonine to lysine. (I) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD <0.01 (1 heterozygote, 0 homozygotes). (SP) 0309 - An alternative amino acid change at the same position has been observed in gnomAD (v2: 13 heterozygotes, 0 homozygotes). (I) 0502 - Missense variant with conflicting in silico predictions and uninformative conservation. (I) 0600 - Variant is located in the annotated A-band with a PSI score of 100 (PMID: 25589632). (I) 0708 - Another missense variant comparable to the one identified in this case has conflicting previous evidence for pathogenicity. p.(Thr25601Met) has been classified as both likely benign and a VUS by diagnostic laboratories in ClinVar. (I) 0807 - This variant has no previous evidence of pathogenicity. (I) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1206 - This variant has been shown to be paternally inherited (by trio analysis). (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.72

BayesDel_addAF

Benign

-0.10

BayesDel_noAF

Benign

-0.28

CADD

Benign

(source)

DANN

Benign

0.89

Eigen

Pathogenic

0.74

Eigen_PC

Pathogenic

0.81

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.93

M_CAP

Benign

0.041

MetaRNN

Benign

0.28

MetaSVM

Benign

-0.83

MutationAssessor

Benign

0.68

PhyloP100

9.9

PrimateAI

Uncertain

0.74

PROVEAN

Pathogenic

-4.4

REVEL

Uncertain

0.37

Sift

Uncertain

0.0030

Polyphen

1.0

Vest4

0.47

MutPred

0.42

Gain of ubiquitination at T23960 (P = 0.023)

MVP

0.27

MPC

0.37

ClinPred

0.45

GERP RS

5.9

Mutation Taster

=69/31

polymorphism

(source)

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

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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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over