rs777369921
Positions:
Variant summary
Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_ModeratePM2PP3_Strong
The NM_001267550.2(TTN):c.9164-2A>T variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000031 in 1,613,942 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).
Frequency
Genomes: 𝑓 0.000020 ( 0 hom., cov: 33)
Exomes 𝑓: 0.0000014 ( 0 hom. )
Consequence
TTN
NM_001267550.2 splice_acceptor
NM_001267550.2 splice_acceptor
Scores
5
1
1
Splicing: ADA: 1.000
2
Clinical Significance
Conservation
PhyloP100: 7.47
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]
Genome browser will be placed here
ACMG classification
Classification made for transcript
Verdict is Likely_pathogenic. Variant got 8 ACMG points.
PVS1
?
Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.0013058458 fraction of the gene. Cryptic splice site detected, with MaxEntScore 7.7, offset of 12, new splice context is: ttttcctgctcgtcatatAGaat. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
PM2
?
Very rare variant in population databases, with high coverage;
PP3
?
Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
|---|---|---|---|---|---|---|---|
| TTN | NM_001267550.2 | c.9164-2A>T | splice_acceptor_variant | ENST00000589042.5 | |||
| TTN | NM_133379.5 | c.9164-2A>T | splice_acceptor_variant | ENST00000360870.10 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|
| TTN | ENST00000360870.10 | c.9164-2A>T | splice_acceptor_variant | 5 | NM_133379.5 | ||||
| TTN | ENST00000589042.5 | c.9164-2A>T | splice_acceptor_variant | 5 | NM_001267550.2 | P1 | |||
| TTN-AS1 | ENST00000659121.1 | n.1592+3789T>A | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes ? AF: 0.0000197 AC: 3AN: 152234Hom.: 0 Cov.: 33
GnomAD3 genomes
?
AF:
AC:
3
AN:
152234
Hom.:
Cov.:
33
Gnomad AFR
AF:
Gnomad AMI
AF:
Gnomad AMR
AF:
Gnomad ASJ
AF:
Gnomad EAS
AF:
Gnomad SAS
AF:
Gnomad FIN
AF:
Gnomad MID
AF:
Gnomad NFE
AF:
Gnomad OTH
AF:
GnomAD3 exomes AF: 0.00000399 AC: 1AN: 250418Hom.: 0 AF XY: 0.00 AC XY: 0AN XY: 135352
GnomAD3 exomes
AF:
AC:
1
AN:
250418
Hom.:
AF XY:
AC XY:
0
AN XY:
135352
Gnomad AFR exome
AF:
Gnomad AMR exome
AF:
Gnomad ASJ exome
AF:
Gnomad EAS exome
AF:
Gnomad SAS exome
AF:
Gnomad FIN exome
AF:
Gnomad NFE exome
AF:
Gnomad OTH exome
AF:
GnomAD4 exome AF: 0.00000137 AC: 2AN: 1461708Hom.: 0 Cov.: 36 AF XY: 0.00000138 AC XY: 1AN XY: 727160
GnomAD4 exome
AF:
AC:
2
AN:
1461708
Hom.:
Cov.:
36
AF XY:
AC XY:
1
AN XY:
727160
Gnomad4 AFR exome
AF:
Gnomad4 AMR exome
AF:
Gnomad4 ASJ exome
AF:
Gnomad4 EAS exome
AF:
Gnomad4 SAS exome
AF:
Gnomad4 FIN exome
AF:
Gnomad4 NFE exome
AF:
Gnomad4 OTH exome
AF:
GnomAD4 genome ? AF: 0.0000197 AC: 3AN: 152234Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2AN XY: 74374
GnomAD4 genome
?
AF:
AC:
3
AN:
152234
Hom.:
Cov.:
33
AF XY:
AC XY:
2
AN XY:
74374
Gnomad4 AFR
AF:
Gnomad4 AMR
AF:
Gnomad4 ASJ
AF:
Gnomad4 EAS
AF:
Gnomad4 SAS
AF:
Gnomad4 FIN
AF:
Gnomad4 NFE
AF:
Gnomad4 OTH
AF:
Bravo
AF:
ExAC
?
AF:
AC:
1
ClinVar
Significance: Uncertain significance
Submissions summary: Uncertain:2
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
| Uncertain significance, criteria provided, single submitter | clinical testing | Invitae | Sep 24, 2021 | This variant is located in the I band of TTN (PMID: 25589632). Truncating variants in this region have been shown to be highly prevalent in the general population and unaffected individuals (PMID: 26701604, 22335739). However, truncating variants in this region have also been reported in individuals affected with autosomal recessive centronuclear myopathy (PMID: 23975875). 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. ClinVar contains an entry for this variant (Variation ID: 223344). This variant has not been reported in the literature in individuals affected with TTN-related conditions. This variant is present in population databases (rs777369921, ExAC 0.01%). This sequence change affects an acceptor splice site in intron 38 of the TTN gene. It is expected to disrupt RNA splicing and likely results in a truncated or disrupted TTN protein. - |
Primary dilated cardiomyopathy Uncertain:1
| Uncertain significance, criteria provided, single submitter | research | Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust | Oct 08, 2014 | This TTN truncating variant (TTNtv) was identified in one individual in this cohort and is located in an exon that is highly expressed in the heart. In the seven cohorts assessed, TTNtv were found in 14% of ambulant DCM, 22% end-stage or familial DCM, and 2% controls. Heterozygous nonsense, frameshift and canonical splice-disrupting variants found in constitutive and other highly utilised exons are highly likely to be pathogenic when identified in individuals with phenotypically confirmed DCM. TTNtv found incidentally in healthy individuals (excluding familial assessment of DCM relatives) are thought to have low penetrance, particularly when identified in exons that are not constitutively expressed in the heart. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
BayesDel_addAF
Pathogenic
D
BayesDel_noAF
Pathogenic
CADD
Pathogenic
DANN
Uncertain
Eigen
Pathogenic
Eigen_PC
Pathogenic
FATHMM_MKL
Pathogenic
D
MutationTaster
Benign
D;D;D;D;D;D;D
GERP RS
Splicing
Name
Calibrated prediction
Score
Prediction
dbscSNV1_ADA
Pathogenic
dbscSNV1_RF
Pathogenic
SpliceAI score (max)
Details are displayed if max score is > 0.2
DS_AG_spliceai
Position offset: -14
DS_AL_spliceai
Position offset: -2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at