RYR1 and cardiac arrhythmia: Among three isoforms that encode RyR genes (RYR), RYR2 is expressed predominantly in cardiac muscle (Avila et al., 2019), and it has been reported to be associated with cardiac diseases such as arrhythmias and sudden cardiac death (SCD) (Napolitano and Priori, 2007; Steinberg et al., 2023).