2-178794464-C-T

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.1333G>A(p.Ala445Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000289 in 1,614,194 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 11/19 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. A445S) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00026 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00029 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:8B:7

Conservation

PhyloP100: 1.65

Publications

12 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 Gene-Disease associations (from GenCC):

dilated cardiomyopathy
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
dilated cardiomyopathy 1G
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
early-onset myopathy with fatal cardiomyopathy
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Labcorp Genetics (formerly Invitae)
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: Orphanet, ClinGen, Ambry Genetics, Labcorp Genetics (formerly Invitae)
tibial muscular dystrophy
Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: ClinGen, Orphanet, Ambry Genetics, Labcorp Genetics (formerly Invitae)
autosomal recessive limb-girdle muscular dystrophy type 2J
Inheritance: AR Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, Labcorp Genetics (formerly Invitae)
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
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
hypertrophic cardiomyopathy 9
Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
arrhythmogenic right ventricular cardiomyopathy
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

TTN 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 (MetaRNN=0.027612716).

BP6

Variant 2-178794464-C-T is Benign according to our data. Variant chr2-178794464-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 178276.

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	UniProt
TTN	NM_001267550.2	MANE Select	c.1333G>A	p.Ala445Thr	missense	Exon 8 of 363	NP_001254479.2	Q8WZ42-12
TTN	NM_001256850.1		c.1333G>A	p.Ala445Thr	missense	Exon 8 of 313	NP_001243779.1	Q8WZ42-1
TTN	NM_133378.4		c.1333G>A	p.Ala445Thr	missense	Exon 8 of 312	NP_596869.4	Q8WZ42-11

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
TTN	ENST00000589042.5	TSL:5 MANE Select	c.1333G>A	p.Ala445Thr	missense	Exon 8 of 363	ENSP00000467141.1	Q8WZ42-12
TTN	ENST00000446966.2	TSL:1	c.1333G>A	p.Ala445Thr	missense	Exon 8 of 361	ENSP00000408004.2	A0A1B0GXE3
TTN	ENST00000436599.2	TSL:1	c.1333G>A	p.Ala445Thr	missense	Exon 8 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes

AF:

0.000263

AC:

AN:

152220

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000723

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000393

Gnomad ASJ

AF:

0.00231

Gnomad EAS

AF:

0.00154

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000191

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.000219

AC:

AN:

251358

AF XY:

0.000250

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000434

Gnomad ASJ exome

AF:

0.00169

Gnomad EAS exome

AF:

0.0000544

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000150

Gnomad OTH exome

AF:

0.000489

GnomAD4 exome

AF:

0.000292

AC:

427

AN:

1461856

Hom.:

Cov.:

AF XY:

0.000303

AC XY:

220

AN XY:

727238

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.000380

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00199

AC:

AN:

26136

East Asian (EAS)

AF:

0.000101

AC:

AN:

39698

South Asian (SAS)

AF:

0.0000580

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.0000187

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.000290

AC:

322

AN:

1111986

Other (OTH)

AF:

0.000414

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.464

Heterozygous variant carriers

113

141

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

100

<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:

0.000263

AC:

AN:

152338

Hom.:

Cov.:

AF XY:

0.000228

AC XY:

AN XY:

74490

show subpopulations

African (AFR)

AF:

0.0000721

AC:

AN:

41590

American (AMR)

AF:

0.000392

AC:

AN:

15304

Ashkenazi Jewish (ASJ)

AF:

0.00231

AC:

AN:

3470

East Asian (EAS)

AF:

0.00154

AC:

AN:

5184

South Asian (SAS)

AF:

0.000207

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10616

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000191

AC:

AN:

68028

Other (OTH)

AF:

0.000473

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.489

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:

0.000275

Hom.:

Bravo

AF:

0.000246

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000581

AC:

ExAC

AF:

0.000231

AC:

Asia WGS

AF:

0.000867

AC:

AN:

3476

EpiCase

AF:

0.000273

EpiControl

AF:

0.000178

ClinVar

ClinVar submissions

Significance:Conflicting classifications of pathogenicity

Revision:criteria provided, conflicting classifications

View on ClinVar

Pathogenic

VUS

Benign

Condition

not provided (5)

not specified (3)

Autosomal recessive limb-girdle muscular dystrophy type 2J (1)

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

Cardiovascular phenotype (1)

Dilated cardiomyopathy 1G (1)

Early-onset myopathy with fatal cardiomyopathy (1)

Myopathy, myofibrillar, 9, with early respiratory failure (1)

Tibial muscular dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.097

BayesDel_addAF

Benign

-0.31

BayesDel_noAF

Benign

-0.37

CADD

Uncertain

(source)

DANN

Benign

0.97

Eigen

Uncertain

0.45

Eigen_PC

Uncertain

0.52

FATHMM_MKL

Uncertain

0.83

LIST_S2

Benign

0.85

M_CAP

Benign

0.033

MetaRNN

Benign

0.028

MetaSVM

Benign

-0.84

PhyloP100

1.6

PrimateAI

Uncertain

0.52

PROVEAN

Benign

-1.9

REVEL

Benign

0.15

Sift

Benign

0.14

Sift4G

Uncertain

0.056

Polyphen

0.98

Vest4

0.39

MVP

0.21

MPC

0.23

ClinPred

0.061

GERP RS

5.9

PromoterAI

-0.0016

Neutral

(source)

Mutation Taster

=81/19

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

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over