Total submissions: 4
Submitter | RCV | SCV | Clinical significance | Condition | Last evaluated | Review status | Method | Comment |
---|---|---|---|---|---|---|---|---|
Cardiovascular Biomedical Research Unit, |
RCV000209451 | SCV000189781 | likely pathogenic | Primary dilated cardiomyopathy | 2014-10-08 | criteria provided, single submitter | research | 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. |
Invitae | RCV000693549 | SCV000821422 | pathogenic | Dilated cardiomyopathy 1G; Autosomal recessive limb-girdle muscular dystrophy type 2J | 2022-07-11 | criteria provided, single submitter | clinical testing | 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). ClinVar contains an entry for this variant (Variation ID: 223377). This variant is also known as c.56572C>T, p.Arg18858X. This premature translational stop signal has been observed in individuals with dilated cardiomyopathy (PMID: 22335739, 25589632, 27532257; Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Arg20499*) in the TTN gene. While this is not anticipated to result in nonsense mediated decay, it is expected to create a truncated TTN protein. For these reasons, this variant has been classified as Pathogenic. |
Ambry Genetics | RCV002336586 | SCV002619012 | pathogenic | Cardiovascular phenotype | 2023-03-20 | criteria provided, single submitter | clinical testing | The p.R11434* pathogenic mutation (also known as c.34300C>T), located in coding exon 131 of the TTN gene, results from a C to T substitution at nucleotide position 34300. This changes the amino acid from an arginine to a stop codon within coding exon 131. 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 variant (also described as NM_001256850.1:c.56572C>T, p.R18858X and NM_001267550.1:c.61495C>T, p.R20499X) has been detected in individuals reported to have dilated cardiomyopathy (DCM) and in clinical and genetic DCM testing cohorts (Herman DS et al. N Engl J Med, 2012 Feb;366:619-28; Roberts AM et al. Sci Transl Med. 2015 Jan;7(270):270ra6; Walsh R et al. Genet Med, 2017 02;19:192-203; Ambry internal data). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). 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 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). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. |
CHEO Genetics Diagnostic Laboratory, |
RCV003486767 | SCV004240045 | pathogenic | Cardiomyopathy | 2023-04-12 | criteria provided, single submitter | clinical testing |