Translating GWAS-identified loci for cardiac rhythm and rate using an in vivo image- and CRISPR/Cas9-based approach

Sci Rep. 2020 Jul 16;10(1):11831. doi: 10.1038/s41598-020-68567-1.


A meta-analysis of genome-wide association studies (GWAS) identified eight loci that are associated with heart rate variability (HRV), but candidate genes in these loci remain uncharacterized. We developed an image- and CRISPR/Cas9-based pipeline to systematically characterize candidate genes for HRV in live zebrafish embryos. Nine zebrafish orthologues of six human candidate genes were targeted simultaneously in eggs from fish that transgenically express GFP on smooth muscle cells (Tg[acta2:GFP]), to visualize the beating heart. An automated analysis of repeated 30 s recordings of beating atria in 381 live, intact zebrafish embryos at 2 and 5 days post-fertilization highlighted genes that influence HRV (hcn4 and si:dkey-65j6.2 [KIAA1755]); heart rate (rgs6 and hcn4); and the risk of sinoatrial pauses and arrests (hcn4). Exposure to 10 or 25 µM ivabradine-an open channel blocker of HCNs-for 24 h resulted in a dose-dependent higher HRV and lower heart rate at 5 days post-fertilization. Hence, our screen confirmed the role of established genes for heart rate and rhythm (RGS6 and HCN4); showed that ivabradine reduces heart rate and increases HRV in zebrafish embryos, as it does in humans; and highlighted a novel gene that plays a role in HRV (KIAA1755).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Bradycardia / diagnostic imaging
  • Bradycardia / genetics*
  • Bradycardia / metabolism
  • Bradycardia / physiopathology
  • CRISPR-Cas Systems
  • Cardiovascular Agents / pharmacology
  • Embryo, Nonmammalian
  • Genes, Reporter
  • Genome-Wide Association Study
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Heart Rate / drug effects
  • Heart Rate / physiology*
  • Humans
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / antagonists & inhibitors
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / genetics*
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / metabolism
  • Ivabradine / pharmacology
  • Meta-Analysis as Topic
  • Myocardial Contraction / drug effects
  • Myocardial Contraction / physiology*
  • Myocytes, Smooth Muscle / cytology
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / metabolism
  • Optical Imaging / methods
  • Pleckstrin Homology Domains / genetics
  • RGS Proteins / genetics*
  • RGS Proteins / metabolism
  • Zebrafish


  • Cardiovascular Agents
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
  • RGS Proteins
  • Green Fluorescent Proteins
  • Ivabradine