2-178553526-G-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Strong

The NM_001267550.2(TTN):c.89479C>A(p.Pro29827Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000093 in 1,613,174 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict 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. P29827A) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000053 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000097 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 4.94

Publications

3 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 -4 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.035618156).

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.89479C>A	p.Pro29827Thr	missense	Exon 334 of 363	NP_001254479.2
TTN	NM_001256850.1		c.84556C>A	p.Pro28186Thr	missense	Exon 284 of 313	NP_001243779.1
TTN	NM_133378.4		c.81775C>A	p.Pro27259Thr	missense	Exon 283 of 312	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.89479C>A	p.Pro29827Thr	missense	Exon 334 of 363	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.89323C>A	p.Pro29775Thr	missense	Exon 332 of 361	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.89203C>A	p.Pro29735Thr	missense	Exon 332 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.0000526

AC:

AN:

152178

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:

0.00124

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000226

AC:

AN:

247822

AF XY:

0.000298

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:

0.0000267

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000972

AC:

142

AN:

1460878

Hom.:

Cov.:

AF XY:

0.000143

AC XY:

104

AN XY:

726684

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33446

American (AMR)

AF:

0.00

AC:

AN:

44666

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26056

East Asian (EAS)

AF:

0.00

AC:

AN:

39694

South Asian (SAS)

AF:

0.00143

AC:

123

AN:

86128

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53324

Middle Eastern (MID)

AF:

0.000347

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.0000144

AC:

AN:

1111466

Other (OTH)

AF:

0.0000166

AC:

AN:

60336

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.483

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:

0.0000525

AC:

AN:

152296

Hom.:

Cov.:

AF XY:

0.0000672

AC XY:

AN XY:

74456

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41566

American (AMR)

AF:

0.00

AC:

AN:

15290

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5182

South Asian (SAS)

AF:

0.00124

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10608

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

68032

Other (OTH)

AF:

0.00

AC:

AN:

2114

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

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:

0.0000312

Hom.:

Bravo

AF:

0.0000113

ExAC

AF:

0.000265

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000594

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

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

Uncertain:1

Nov 15, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces proline with threonine at codon 29827 of the TTN protein (p.Pro29827Thr). There is a small physicochemical difference between proline and threonine. This variant is present in population databases (rs201620815, ExAC 0.2%). This variant has not been reported in the literature in individuals with TTN-related conditions. ClinVar contains an entry for this variant (Variation ID: 191859). This variant is located in the A band of TTN (PMID: 25589632). Variants in this region may be relevant for cardiac or neuromuscular disorders (PMID: 25589632, 23975875). Algorithms developed to predict the effect of missense changes on protein structure and function are unavailable for the TTN gene. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

not provided

Uncertain:1

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:research

Cardiovascular phenotype

Uncertain:1

Jan 09, 2020

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.P20762T variant (also known as c.62284C>A), located in coding exon 161 of the TTN gene, results from a C to A substitution at nucleotide position 62284. The proline at codon 20762 is replaced by threonine, an amino acid with highly similar properties. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.17

BayesDel_addAF

Benign

-0.37

BayesDel_noAF

Benign

-0.32

CADD

Benign

(source)

DANN

Benign

0.92

Eigen

Pathogenic

0.79

Eigen_PC

Pathogenic

0.77

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Benign

0.82

M_CAP

Benign

0.023

MetaRNN

Benign

0.036

MetaSVM

Benign

-0.34

MutationAssessor

Benign

1.4

PhyloP100

4.9

PrimateAI

Benign

0.44

PROVEAN

Pathogenic

-5.0

REVEL

Benign

0.25

Sift

Benign

0.038

Polyphen

1.0

Vest4

0.40

MutPred

0.34

Loss of disorder (P = 0.1025)

MVP

0.44

MPC

0.49

ClinPred

0.21

GERP RS

5.6

Mutation Taster

=80/20

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

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over