rs397517594
Positions:
Variant summary
Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2PP3_Strong
The NM_001267550.2(TTN):c.48638+5G>T variant causes a splice donor 5th base, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Genomes: not found (cov: 32)
Consequence
TTN
NM_001267550.2 splice_donor_5th_base, intron
NM_001267550.2 splice_donor_5th_base, intron
Scores
2
Splicing: ADA: 1.000
2
Clinical Significance
Conservation
PhyloP100: 4.42
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]
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ACMG classification
Classification made for transcript
Verdict is Likely_pathogenic. Variant got 6 ACMG points.
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.48638+5G>T | splice_donor_5th_base_variant, intron_variant | ENST00000589042.5 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
TTN | ENST00000589042.5 | c.48638+5G>T | splice_donor_5th_base_variant, intron_variant | 5 | NM_001267550.2 | P1 | |||
TTN-AS1 | ENST00000659121.1 | n.502+17621C>A | intron_variant, non_coding_transcript_variant |
Frequencies
GnomAD3 genomes ? Cov.: 32
GnomAD3 genomes
?
Cov.:
32
GnomAD4 exome Cov.: 32
GnomAD4 exome
Cov.:
32
GnomAD4 genome ? Cov.: 32
GnomAD4 genome
?
Cov.:
32
ClinVar
Significance: Conflicting classifications of pathogenicity
Submissions summary: Pathogenic:1Uncertain:3
Revision: criteria provided, conflicting classifications
LINK: link
Submissions by phenotype
not provided Pathogenic:1
Likely pathogenic, criteria provided, single submitter | clinical testing | GeneDx | Nov 30, 2017 | The c.43715+5 G>T likely pathogenic variant in the TTN gene has not been reported as a pathogenic or benign to our knowledge. The c.43715+5 G>T variant is not observed in large population cohorts (Lek et al., 2016). This substitution occurs at a nucleotide position that is conserved across species, and in silico splice prediction programs predict this variant results in loss of the natural splice donor site for intron 209 which is predicted to cause abnormal gene splicing. This variant is predicted to lead to either an abnormal message that is subject to nonsense-mediated mRNA decay, or to an abnormal protein product if the message is used for protein translation. Other splice site variants in TTN, including additional variants at the +5 position, have been reported in HGMD in association with DCM (Stenson et al., 2014). Although truncating TTN variants have been reported in approximately 3% of control alleles (Herman et al., 2012), the c.43715+5 G>T variant is located in the A-band region of titin, where the majority of truncating pathogenic variants associated with DCM have been reported (Herman et al., 2012). Nonetheless, in the absence of functional mRNA studies, the physiological consequences of this variant cannot be precisely determined. - |
not specified Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine | Feb 25, 2013 | The 40934+5G>T variant in TTN has not been reported in the literature nor previo usly identified by our laboratory. This variant has also not been identified in large and broad European American and African American populations by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/EVS), though it may be co mmon in other populations. It is located in the 5' splice region, and computatio nal tools do not provide strong support for or against an impact to splicing. Ad ditional information is needed to fully assess the clinical significance of this variant. - |
Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Invitae | Oct 12, 2023 | This sequence change falls in intron 259 of the TTN gene. It does not directly change the encoded amino acid sequence of the TTN protein. It affects a nucleotide within the consensus splice site. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TTN-related conditions. ClinVar contains an entry for this variant (Variation ID: 47023). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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). 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. - |
Cardiovascular phenotype Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Ambry Genetics | Mar 09, 2022 | The c.21443+5G>T intronic variant results from a G to T substitution 5 nucleotides after coding exon 86 in the TTN gene. This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
BayesDel_noAF
Benign
CADD
Uncertain
DANN
Benign
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_DL_spliceai
Position offset: 5
Find out detailed SpliceAI scores and Pangolin per-transcript scores at