These experiments revealed an amelioration of Ca2+ transients amplitude (F/F0 – ratio between peak and baseline) in HO-CMs upon infection with AAV-9-hCASQ2-RFP (HO-CASQ2) (Figure 6a; Supplementary Figure 7A), which reverted to a phenotype akin to that recorded in WT-CMs (representative profiles are shown in the Supplementary Figure 7A). The gene discussed is CASQ2; the disease is infection.