Genetic Variant NM_001267550.2:c.23100A>T (chr2-178720662-T-A) – 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.23100A>T(p.Ala7700Ala) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000127 in 1,572,566 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely benign (★).

Frequency

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

Exomes 𝑓: 7.0e-7 ( 0 hom. )

Consequence

TTN
NM_001267550.2 splice_region, synonymous

Scores

Splicing: ADA: 0.00001957

Clinical Significance

Likely benign criteria provided, single submitter B:1

Conservation

PhyloP100: 0.707

Publications

0 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 -5 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.48).

BP6

Variant 2-178720662-T-A is Benign according to our data. Variant chr2-178720662-T-A is described in ClinVar as Likely_benign. ClinVar VariationId is 466918.Status of the report is criteria_provided_single_submitter, 1 stars.

BP7

Synonymous conserved (PhyloP=0.707 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.23100A>T	p.Ala7700Ala	splice_region synonymous	Exon 80 of 363	NP_001254479.2
TTN	NM_001256850.1		c.22149A>T	p.Ala7383Ala	splice_region synonymous	Exon 78 of 313	NP_001243779.1
TTN	NM_133378.4		c.19368A>T	p.Ala6456Ala	splice_region synonymous	Exon 77 of 312	NP_596869.4

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTN	ENST00000589042.5	TSL:5 MANE Select	c.23100A>T	p.Ala7700Ala	splice_region synonymous	Exon 80 of 363	ENSP00000467141.1
TTN	ENST00000446966.2	TSL:1	c.23100A>T	p.Ala7700Ala	splice_region synonymous	Exon 80 of 361	ENSP00000408004.2
TTN	ENST00000436599.2	TSL:1	c.22824A>T	p.Ala7608Ala	splice_region synonymous	Exon 78 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes

AF:

0.00000660

AC:

AN:

151572

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000243

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000476

AC:

AN:

210226

AF XY:

0.00000872

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:

0.00000995

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

7.04e-7

AC:

AN:

1420994

Hom.:

Cov.:

AF XY:

0.00000142

AC XY:

AN XY:

704482

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

31204

American (AMR)

AF:

0.00

AC:

AN:

35420

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

23956

East Asian (EAS)

AF:

0.00

AC:

AN:

39334

South Asian (SAS)

AF:

0.00

AC:

AN:

78716

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51112

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5518

European-Non Finnish (NFE)

AF:

9.11e-7

AC:

AN:

1097274

Other (OTH)

AF:

0.00

AC:

AN:

58460

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.00000660

AC:

AN:

151572

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

73982

show subpopulations

African (AFR)

AF:

0.0000243

AC:

AN:

41212

American (AMR)

AF:

0.00

AC:

AN:

15204

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5166

South Asian (SAS)

AF:

0.00

AC:

AN:

4788

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10502

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67920

Other (OTH)

AF:

0.00

AC:

AN:

2086

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

Nov 23, 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

-0.48

CADD

Benign

3.8

(source)

DANN

Benign

0.59

PhyloP100

0.71

Mutation Taster

=69/31

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Benign

0.000020

dbscSNV1_RF

Benign

0.0

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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over