Total submissions: 2
Submitter | RCV | SCV | Clinical significance | Condition | Last evaluated | Review status | Method | Comment |
---|---|---|---|---|---|---|---|---|
Invitae | RCV000703837 | SCV000832759 | likely pathogenic | Dilated cardiomyopathy 1G; Autosomal recessive limb-girdle muscular dystrophy type 2J | 2023-12-06 | criteria provided, single submitter | clinical testing | This sequence change creates a premature translational stop signal (p.Glu33910*) in the TTN gene. While this is not anticipated to result in nonsense mediated decay, it is expected to create a truncated 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: 580335). This variant is located in the M band of TTN (PMID: 25589632). Truncating variants in this region have been previously reported in individuals affected with autosomal recessive myopathy and muscular dystrophy (PMID: 18948003, 23975875, 24395473). Truncating variants in this region have also been identified in individuals affected with autosomal dominant dilated cardiomyopathy and/or cardio-related conditions (PMID: 27869827, 32964742). 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. |
Ambry Genetics | RCV002386262 | SCV002674593 | likely pathogenic | Cardiovascular phenotype | 2022-06-06 | criteria provided, single submitter | clinical testing | The p.E24845* variant (also known as c.74533G>T), located in coding exon 185 of the TTN gene, results from a G to T substitution at nucleotide position 74533. This changes the amino acid from a glutamic acid to a stop codon within coding exon 185. This exon is located in the M-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 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 M-band have been reported in association with autosomal recessive titinopathies, primarily presenting with skeletal myopathy phenotypes (Ceyhan-Birsoy O et al. Neurology. 2013 Oct 1;81(14):1205-14; De Cid R et al. Neurology. 2015;85(24):2126-35). In addition, regardless of their position, TTN truncating variants encoded in constitutive exons (PSI >90%) have been found to be significantly associated with dilated cardiomyopathy (DCM), though 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; Schafer S et al. Nat. Genet., 2017 01;49:46-53). Based on the majority of available evidence to date, this variant is likely to be pathogenic in association with autosomal recessive titinopathy; however, the clinical significance of this alteration with respect to cardiomyopathy remains unclear. |