Genetic Variant TTN:p.Pro11447Pro (chr2-178677238-G-T) – ACMG Classification: Likely_benign (-5 pts)

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 2P and 7B. PM2BP4_StrongBP6_ModerateBP7

The NM_001267550.2(TTN):c.34341C>A(p.Pro11447Pro) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000164 in 1,222,042 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 Likely benign (★). Synonymous variant affecting the same amino acid position (i.e. P11447P) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0000067 ( 0 hom., cov: 26)

Exomes 𝑓: 9.3e-7 ( 0 hom. )

Consequence

TTN
NM_001267550.2 synonymous

Scores

Clinical Significance

Likely benign criteria provided, single submitter B:1

Conservation

PhyloP100: -2.76

Publications

1 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.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.66).

BP6

Variant 2-178677238-G-T is Benign according to our data. Variant chr2-178677238-G-T is described in ClinVar as Likely_benign. ClinVar VariationId is 3761994.Status of the report is criteria_provided_single_submitter, 1 stars.

BP7

Synonymous conserved (PhyloP=-2.76 with no splicing effect.

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.34341C>A	p.Pro11447Pro	synonymous	Exon 147 of 363	NP_001254479.2
TTN	NM_001256850.1		c.33340+383C>A		intron	N/A	NP_001243779.1
TTN	NM_133378.4		c.30559+383C>A		intron	N/A	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.34341C>A	p.Pro11447Pro	synonymous	Exon 147 of 363	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.34341C>A	p.Pro11447Pro	synonymous	Exon 147 of 361	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.34065C>A	p.Pro11355Pro	synonymous	Exon 145 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.00000668

AC:

AN:

149628

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:

0.0000148

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

9.32e-7

AC:

AN:

1072414

Hom.:

Cov.:

AF XY:

0.00000198

AC XY:

AN XY:

506298

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

22588

American (AMR)

AF:

0.00

AC:

AN:

8252

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

14098

East Asian (EAS)

AF:

0.00

AC:

AN:

25922

South Asian (SAS)

AF:

0.00

AC:

AN:

19410

European-Finnish (FIN)

AF:

0.00

AC:

AN:

20980

Middle Eastern (MID)

AF:

0.00

AC:

AN:

2870

European-Non Finnish (NFE)

AF:

0.00000109

AC:

AN:

915144

Other (OTH)

AF:

0.00

AC:

AN:

43150

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

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:

0.00000668

AC:

AN:

149628

Hom.:

Cov.:

AF XY:

0.0000137

AC XY:

AN XY:

72996

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

40470

American (AMR)

AF:

0.00

AC:

AN:

14932

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3448

East Asian (EAS)

AF:

0.00

AC:

AN:

5102

South Asian (SAS)

AF:

0.00

AC:

AN:

4722

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10192

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.0000148

AC:

AN:

67492

Other (OTH)

AF:

0.00

AC:

AN:

2050

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

Alfa

AF:

0.00

Hom.:

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

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

Benign:1

Jul 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely 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

-0.66

CADD

Benign

0.71

(source)

DANN

Benign

0.64

PhyloP100

-2.8

Mutation Taster

=100/0

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.11

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