ClinVar Miner

Submissions for variant NM_001267550.2(TTN):c.64810C>T (p.Arg21604Ter)

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Total submissions: 3
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Submitter RCV SCV Clinical significance Condition Last evaluated Review status Method Comment
Ambry Genetics RCV002363848 SCV002625930 likely pathogenic Cardiovascular phenotype 2024-05-07 criteria provided, single submitter clinical testing The p.R12539* variant (also known as c.37615C>T), located in coding exon 137 of the TTN gene, results from a C to T substitution at nucleotide position 37615. This changes the amino acid from an arginine to a stop codon within coding exon 137. This exon 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 (also noted as p.R21604* (c.64810C>T)) has been reported in association with early-onset atrial fibrillation (Choi SH et al. JAMA, 2018 12;320:2354-2364). This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. While truncating variants in TTN are present in 1-3% of the general population, truncating variants in the A-band are the most common cause of dilated cardiomyopathy (DCM) (Herman DS et al. N. Engl. J. Med., 2012 Feb;366:619-28; Roberts AM et al. Sci Transl Med, 2015 Jan;7:270ra6). TTN truncating variants encoded in constitutive exons (PSI >90%) have been found to be significantly associated with DCM regardless of their position in titin (Schafer S et al. Nat. Genet., 2017 01;49:46-53). This variant is also considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). As such, this alteration is classified as likely pathogenic.
Labcorp Genetics (formerly Invitae), Labcorp RCV003102439 SCV003472559 likely pathogenic Dilated cardiomyopathy 1G; Autosomal recessive limb-girdle muscular dystrophy type 2J 2022-04-07 criteria provided, single submitter clinical testing 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). This premature translational stop signal has been observed in individual(s) with clinical features of TTN-related conditions (PMID: 30535219). This variant is present in population databases (no rsID available, gnomAD 0.0009%). This sequence change creates a premature translational stop signal (p.Arg21604*) in the TTN gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 14388 amino acid(s) of the TTN protein.
Cardiogenetics and Myogenetics Molecular and Cellular Functional Unit, Aphp Sorbonne University-Hopital Pitie Salpetriere RCV004764984 SCV005374931 likely pathogenic Dilated cardiomyopathy 1G 2024-01-06 no assertion criteria provided clinical testing

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