ClinVar Miner

Submissions for variant NM_001267550.2(TTN):c.64094-2A>G

dbSNP: rs876657667
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Total submissions: 3
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Submitter RCV SCV Clinical significance Condition Last evaluated Review status Method Comment
Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine RCV000218778 SCV000271279 likely pathogenic Primary dilated cardiomyopathy 2015-07-16 criteria provided, single submitter clinical testing The c.56390-2A>G variant in TTN has not been previously reported in individuals with cardiomyopathy or in large population studies. This variant occurs in the i nvariant region (+/- 1,2) of the 3' splice consensus sequence and is predicted t o cause altered splicing leading to an abnormal or absent protein. Splicing and other truncating variants in TTN are strongly associated with DCM if they impact the exons encoding for the A-band (Herman 2012, Pugh 2014) and/or an exon that is highly expressed in the heart (Roberts 2015), which is the case for this vari ant. In summary, although additional studies are required to fully establish its clinical significance, the c.56390-2A>G variant is likely pathogenic.
Labcorp Genetics (formerly Invitae), Labcorp RCV002519624 SCV003315743 likely pathogenic Dilated cardiomyopathy 1G; Autosomal recessive limb-girdle muscular dystrophy type 2J 2022-03-11 criteria provided, single submitter clinical testing This sequence change affects an acceptor splice site in intron 307 of the TTN gene. It is expected to disrupt RNA splicing and likely results in a truncated or disrupted TTN protein. 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: 228302). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant is located in the A band of TTN (PMID: 25589632). Truncating variants in this region are significantly overrepresented in patients affected with dilated cardiomyopathy (PMID: 25589632). Truncating variants in this region have also been reported in individuals affected with autosomal recessive centronuclear myopathy (PMID: 23975875).
Ambry Genetics RCV004686579 SCV005173502 uncertain significance Cardiovascular phenotype 2024-04-26 criteria provided, single submitter clinical testing The c.36899-2A>G intronic variant results from an A to G substitution two nucleotides upstream from coding exon 135 in the TTN gene. Exon 134 is located in the A-band region of the N2-B isoform of the titin protein and is constitutively expressed in TTN transcripts (percent spliced in or PSI 100%). This alteration has been reported in a dilated cardiomyopathy (DCM) cohort (Vissing CR et al. J Med Genet, 2021 Dec;58:832-841). In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site and will result in the creation or strengthening of a novel splice acceptor site. This alteration disrupts the canonical splice site and is expected to cause aberrant splicing. However, although direct evidence is unavailable, this alteration is predicted to result in an in-frame transcript that is not expected to trigger nonsense-mediated mRNA decay. The exact functional effect of the predicted splice impact is unknown. This nucleotide position is highly conserved in available vertebrate species. Based on the available evidence, the clinical significance of this variant remains unclear.

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