An In Vivo Cardiac Assay to Determine the Functional Consequences of Putative Long QT Syndrome Mutations

• Published in: Circulation research Vol. 112; no. 5; pp. 826 - 830
• Main Authors: Jou, Chuanchau J, Barnett, Spencer M, Bian, Jian-Tao, Weng, H Cindy, Sheng, Xiaoming, Tristani-Firouzi, Martin
• Format: Journal Article
• Language: English
• Published: United States American Heart Association, Inc 01.03.2013
• Subjects: Algorithms; Animals; Disease Models, Animal; Ether-A-Go-Go Potassium Channels - genetics; Gene Knockdown Techniques; Genetic Predisposition to Disease - genetics; Genetic Testing; Heart - physiopathology; High-Throughput Screening Assays - methods; Long QT Syndrome - genetics; Long QT Syndrome - physiopathology; Mutation - genetics; Polymorphism, Genetic - genetics; Predictive Value of Tests; Zebrafish - embryology; Zebrafish - genetics; Zebrafish Proteins - genetics
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/CIRCRESAHA.112.300664

RATIONALE:Genetic testing for Long QT Syndrome is now a standard and integral component of clinical cardiology. A major obstacle to the interpretation of genetic findings is the lack of robust functional assays to determine the pathogenicity of identified gene variants in a high-throughput manner. OBJECTIVE:The goal of this study was to design and test a high-throughput in vivo cardiac assay to distinguish between disease-causing and benign KCNH2 (hERG1) variants, using the zebrafish as a model organism. METHODS AND RESULTS:We tested the ability of previously characterized Long QT Syndrome hERG1 mutations and polymorphisms to restore normal repolarization in the kcnh2-knockdown embryonic zebrafish. The cardiac assay correctly identified a benign variant in 9 of 10 cases (negative predictive value 90%), whereas correctly identifying a disease-causing variant in 39/39 cases (positive predictive value 100%). CONCLUSIONS:The in vivo zebrafish cardiac assay approaches the accuracy of the current benchmark in vitro assay for the detection of disease-causing mutations, and is far superior in terms of throughput rate. Together with emerging algorithms for interpreting a positive long QT syndrome genetic test, the zebrafish cardiac assay provides an additional tool for the final determination of pathogenicity of gene variants identified in long QT syndrome genetic screening.