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Hoffmann S, Paone C, Sumer SA, Diebold S, Weiss B, Roeth R, Clauss S, Klier I, Kääb S, Schulz A, Wild PS, Ghrib A, Zeller T, Schnabel RB, Just S, Rappold GA. Functional Characterization of Rare Variants in the SHOX2 Gene Identified in Sinus Node Dysfunction and Atrial Fibrillation. Front Genet 2019; 10:648. [PMID: 31354791 PMCID: PMC6637028 DOI: 10.3389/fgene.2019.00648] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/19/2019] [Indexed: 12/21/2022] Open
Abstract
Sinus node dysfunction (SND) and atrial fibrillation (AF) often coexist; however, the molecular mechanisms linking both conditions remain elusive. Mutations in the homeobox-containing SHOX2 gene have been recently associated with early-onset and familial AF. Shox2 is a key regulator of sinus node development, and its deficiency leads to bradycardia, as demonstrated in animal models. To provide an extended SHOX2 gene analysis in patients with distinct arrhythmias, we investigated SHOX2 as a susceptibility gene for SND and AF by screening 98 SND patients and 450 individuals with AF. The functional relevance of the novel mutations was investigated in vivo and in vitro, together with the previously reported p.H283Q variant. A heterozygous missense mutation (p.P33R) was identified in the SND cohort and four heterozygous variants (p.G77D, p.L129=, p.L130F, p.A293=) in the AF cohort. Overexpression of the pathogenic predicted mutations in zebrafish revealed pericardial edema for p.G77D and the positive control p.H283Q, whereas the p.P33R and p.A293= variants showed no effect. In addition, a dominant-negative effect with reduced heart rates was detected for p.G77D and p.H283Q. In vitro reporter assays demonstrated for both missense variants p.P33R and p.G77D significantly impaired transactivation activity, similar to the described p.H283Q variant. Also, a reduced Bmp4 target gene expression was revealed in zebrafish hearts upon overexpression of the p.P33R mutant. This study associates additional rare variants in the SHOX2 gene implicated in the susceptibility to distinct arrhythmias and allows frequency estimations in the AF cohort (3/990). We also demonstrate for the first time a genetic link between SND and AF involving SHOX2. Moreover, our data highlight the importance of functional investigations of rare variants.
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Affiliation(s)
- Sandra Hoffmann
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Christoph Paone
- Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Simon A Sumer
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Sabrina Diebold
- Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Birgit Weiss
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany
| | - Ralph Roeth
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany
| | - Sebastian Clauss
- Department of Medicine I, Klinikum Grosshadern, University of Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Ina Klier
- Department of Medicine I, Klinikum Grosshadern, University of Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Stefan Kääb
- Department of Medicine I, Klinikum Grosshadern, University of Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Andreas Schulz
- Preventive Cardiology and Preventive Medicine, Center for Cardiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Philipp S Wild
- Preventive Cardiology and Preventive Medicine, Center for Cardiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Adil Ghrib
- Department of General and Interventional Cardiology, University Heart Center Hamburg (UHZ), University Hospital Hamburg/Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Hamburg/Kiel/Luebeck, Hamburg, Germany
| | - Tanja Zeller
- Department of General and Interventional Cardiology, University Heart Center Hamburg (UHZ), University Hospital Hamburg/Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Hamburg/Kiel/Luebeck, Hamburg, Germany
| | - Renate B Schnabel
- Department of General and Interventional Cardiology, University Heart Center Hamburg (UHZ), University Hospital Hamburg/Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Hamburg/Kiel/Luebeck, Hamburg, Germany
| | - Steffen Just
- Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Gudrun A Rappold
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany
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