A, Schematic picture showing gRNA-SaCas9 and “reporter” AAV9 co-injected in R176Q/+ mice. The “reporter” virus with cloned targeted sequence was cut by gRNA-SaCas9 but not the control BbsI-SaCas9. The mCherry protein is only expressed in cardiomycytes with SaCas9 expression. B, Representative confocal images of ventricle myocytes from R176Q/+ mice co-injected with Bbsl-SaCas9 (control) + “reporter” and gRNA-SaCas9 (editing) + “reporter”, merged with bright field (BF) and red fluorescence (RFP) signal overlay. Scale bar, 100 μm. C, Bar graph showing percentages of mCherry-positive cardiomyocytes. D-F, Summary data for Ca2+ spark frequency, SR Ca2+ load, and SR Ca2+ transient amplitude. *p<0.05, **p<0.01, ***p<0.001.