RBM20 and familial dilated cardiomyopathy: Using RBM20 knockout mice that developed DCM, they were able to prove that two subsets of circRNAs are formed from TTN—a subgroup whose formation was independent of RBM20 and a subset located in the I-band region whose formation required the activity of RBM20, thus indicating that RBM20 is only essential for the production of circRNAs from a certain region of the TTN gene [63].