chr2-178598763-C-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM1BP4_ModerateBP6

The NM_001267550.2(TTN):c.56947G>A(p.Ala18983Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000103 in 1,612,746 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/20 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. A18983V) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00011 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:11B:3

Conservation

PhyloP100: 2.57

Publications

9 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.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 5 uncertain in NM_001267550.2

BP4

Computational evidence support a benign effect (MetaRNN=0.2572359).

BP6

Variant 2-178598763-C-T is Benign according to our data. Variant chr2-178598763-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 229467.

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.56947G>A	p.Ala18983Thr	missense	Exon 291 of 363	NP_001254479.2	Q8WZ42-12
TTN	NM_001256850.1		c.52024G>A	p.Ala17342Thr	missense	Exon 241 of 313	NP_001243779.1	Q8WZ42-1
TTN	NM_133378.4		c.49243G>A	p.Ala16415Thr	missense	Exon 240 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.56947G>A	p.Ala18983Thr	missense	Exon 291 of 363	ENSP00000467141.1	Q8WZ42-12
TTN	ENST00000446966.2	TSL:1	c.56791G>A	p.Ala18931Thr	missense	Exon 289 of 361	ENSP00000408004.2	A0A1B0GXE3
TTN	ENST00000436599.2	TSL:1	c.56671G>A	p.Ala18891Thr	missense	Exon 289 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes

AF:

0.0000657

AC:

AN:

152092

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:

0.000118

Gnomad OTH

AF:

0.000956

GnomAD2 exomes

AF:

0.0000929

AC:

AN:

247614

AF XY:

0.0000968

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000582

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000179

Gnomad OTH exome

AF:

0.000166

GnomAD4 exome

AF:

0.000107

AC:

156

AN:

1460654

Hom.:

Cov.:

AF XY:

0.0000950

AC XY:

AN XY:

726608

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33394

American (AMR)

AF:

0.0000449

AC:

AN:

44576

Ashkenazi Jewish (ASJ)

AF:

0.0000766

AC:

AN:

26098

East Asian (EAS)

AF:

0.00

AC:

AN:

39638

South Asian (SAS)

AF:

0.00

AC:

AN:

86090

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53394

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5750

European-Non Finnish (NFE)

AF:

0.000135

AC:

150

AN:

1111384

Other (OTH)

AF:

0.0000166

AC:

AN:

60330

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.488

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:

0.0000657

AC:

AN:

152092

Hom.:

Cov.:

AF XY:

0.0000539

AC XY:

AN XY:

74278

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41444

American (AMR)

AF:

0.00

AC:

AN:

15252

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5156

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10620

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000118

AC:

AN:

68002

Other (OTH)

AF:

0.000956

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.520

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:

0.000123

Hom.:

Bravo

AF:

0.0000831

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000245

AC:

ExAC

AF:

0.0000911

AC:

EpiCase

AF:

0.000328

EpiControl

AF:

0.0000593

ClinVar

ClinVar submissions

Significance:Conflicting classifications of pathogenicity

Revision:criteria provided, conflicting classifications

View on ClinVar

Pathogenic

VUS

Benign

Condition

not provided (7)

not specified (3)

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

Cardiomyopathy (1)

Cardiovascular phenotype (1)

TTN-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.75

BayesDel_addAF

Benign

-0.11

BayesDel_noAF

Benign

-0.14

CADD

Benign

(source)

DANN

Benign

0.93

Eigen

Uncertain

0.53

Eigen_PC

Uncertain

0.55

FATHMM_MKL

Uncertain

0.96

LIST_S2

Uncertain

0.91

M_CAP

Benign

0.075

MetaRNN

Benign

0.26

MetaSVM

Benign

-0.54

MutationAssessor

Benign

2.0

PhyloP100

2.6

PrimateAI

Uncertain

0.55

PROVEAN

Uncertain

-2.8

REVEL

Benign

0.21

Sift

Uncertain

0.021

Polyphen

0.92

Vest4

0.42

MVP

0.30

MPC

0.19

ClinPred

0.10

GERP RS

5.9

Mutation Taster

=5/95

disease causing

(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