Provided herein is a gene therapy for JPH2 (Junctophilin-2), e.g., using an adeno-associated virus (AAV) vector. The promoter of the vector may be a MHCK7 promoter or a cardiac troponin T (HTNNT2) promoter. The capsid may be an AAV9 or AAVrh74 capsid or a functional variant thereof. Other promoters or capsids may be used. Further provided are methods of treatment, such as by intravenous, intracoronary, intracarotid or intracardiac administration of the rAAV vector, and other compositions and methods.