A homozygous DSC2 deletion associated with arrhythmogenic cardiomyopathy is caused by uniparental isodisomy. (April 2020)

• Record Type: Journal Article
• Authors: Brodehl, Andreas; Weiss, Jürgen; Debus, Jana Davina; Stanasiuk, Caroline; Klauke, Bärbel; Deutsch, Marcus André; Fox, Henrik; Bax, Jördis; Ebbinghaus, Hans; Gärtner, Anna; Tiesmeier, Jens; Laser, Thorsten; Peterschröder, Andreas; Gerull, Brenda; Gummert, Jan; Paluszkiewicz, Lech; Milting, Hendrik
• Is Part Of: Journal of molecular and cellular cardiology. Volume 141(2020)
• Page Start: 17
• Page End: 29
• Publication Date: 2020-04
• Subjects: ACM Arrhythmogenic Cardiomyopathy -- CGH Comparative Genomic Hybridization -- ECG Electrocardiogram -- EYFP Enhanced Yellow Fluorescence Protein -- GFP Green Fluorescence Protein -- hiPSC Human Induced Pluripotent Stem Cells -- IHC Immunohistochemistry -- MRI Magnetic Resonance Imaging -- NMD Nonsense Mediated mRNA Decay -- PBS Phosphate Buffered Saline -- PEI Polyethylenimine -- PTC Premature Termination Codon -- qRT-PCR Quantitative Real-Time Polymerase Chain Reaction -- ROH Run of Homozygosity -- TBST Tris-Buffered Saline with Tween 20 -- TEM Transmission Electron Microscopy -- UPD Uniparental Isodisomy -- WES Whole Exome Sequencing; Desmocollin-2 -- Desmosomes -- Cardiomyopathy -- Arrhythmogenic right ventricular cardiomyopathy -- Uniparental Isodisomy -- DSC2; Cardiology -- Periodicals; Heart Diseases -- Periodicals; Molecular Biology -- Periodicals; Cardiologie -- Périodiques; Cardiology; Electronic journals; Periodicals; 616.12
• DOI: 10.1016/j.yjmcc.2020.03.006
• Languages: English
• ISSNs: 0022-2828

Abstract

Abstract: Aims: We aimed to unravel the genetic, molecular and cellular pathomechanisms of DSC2 truncation variants leading to arrhythmogenic cardiomyopathy (ACM). Methods and results: We report a homozygous 4-bp DSC2 deletion variant c.1913_1916delAGAA, p.Q638LfsX647 hom causing a frameshift carried by an ACM patient. Whole exome sequencing and comparative genomic hybridization analysis support a loss of heterozygosity in a large segment of chromosome 18 indicating segmental interstitial uniparental isodisomy (UPD). Ultrastructural analysis of the explanted myocardium from a mutation carrier using transmission electron microscopy revealed a partially widening of the intercalated disc. Using qRT-PCR we demonstrated that DSC2 mRNA expression was substantially decreased in the explanted myocardial tissue of the homozygous carrier compared to controls. Western blot analysis revealed absence of both full-length desmocollin-2 isoforms. Only a weak expression of the truncated form of desmocollin-2 was detectable. Immunohistochemistry showed that the truncated form of desmocollin-2 did not localize at the intercalated discs. In vitro, transfection experiments using induced pluripotent stem cell derived cardiomyocytes and HT-1080 cells demonstrated an obvious absence of the mutant truncated desmocollin-2 at the plasma membrane. Immunoprecipitation in combination with fluorescence measurements and Western blot analyses revealed an abnormal secretion of the truncated desmocollin-2. Conclusion: In summary, we unraveled segmental UPD as the likely genetic reason for a small homozygous DSC2 deletion. We conclude that a combination of nonsense mediated mRNA decay and extracellular secretion is involved in DSC2 related ACM. Highlights: We show that DSC2 truncating mutations cause a loss of function mechanism. DSC2 truncating mutations can be recessively inherited. First report, demonstrating that uniparental isodisomy might be involved in ACM.