We next investigated whether E99K-ACTC1 mutants showed any difference in arrhythmogenic event frequency, since clinical and animal studies usually show ECG abnormalities and a varying degree of enhanced arrhythmia in mutation carriers (Arad et al., 2002, Olson et al., 2000, Monserrat et al., 2007, Song et al., 2011, Rowlands et al., 2017). The gene discussed is ACTC1; the disease is cardiac arrhythmia.