In a recent study, although great work was done to demonstrate the role of the titin protein in the observed mouse cardiac toxicity with the AAV9-desmin-hCAPN3 construct but not in non-human primates,47 it was still underappreciated that the observed cardiomyopathy only occurs in the context of the desmin-C3 vector. The gene discussed is DES; the disease is cardiomyopathy.