An In Vivo Cardiac Assay to Determine the Functional Consequences of Putative Long QT Syndrome Mutations
Rationale: Genetic testing for Long QT Syndrome (LQTS) 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 LQTS 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%) while 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 LQTS genetic test, the zebrafish cardiac assay provides an additional tool for the final determination of pathogenicity of gene variants identified in LQTS genetic screening.
- model organism
- sudden death
- genetic testing
- long QT syndrome
- gene mutation
- genetic polymorphism
- genomics, physiological
- Received December 1, 2012.
- Revision received January 3, 2013.
- Accepted January 9, 2013.
- Copyright © 2013, Circulation Research