To investigate the impact of the development of HF on cardiac ADGRG1 expression, we performed TAC surgery, a model of pressure overload-induced hypertrophy and subsequent development of HFrEF [25,30,31], on wild-type mice (C57BL6/J), as confirmed via pressure gradient analysis at 1-week post-TAC (Figure 1A) and via serial echocardiography, which showed decreases in % ejection fraction (%EF, Figure 1B) and % fractional shortening (%FS, Figure 1C), as well as increases in LV volumes and internal diameters (Supplementary Figure S1D–G). The gene discussed is ADGRG1; the disease is hydrops fetalis.