To assess the consequences of altered cTnC in an in vivo system, we began by using CRISPR/Cas9-mediated gene editing to knockout TNNC1 in Xenopus. Loss of the TNNC1 gene did not prevent the early stages of development, and resulted in a dramatic cardiac phenotype in tadpoles consistent with DCM (Figure 4 and Supplementary Video S1). Here, TNNC1 is linked to familial dilated cardiomyopathy.