ADRB1 and familial dilated cardiomyopathy: Therefore, to detect whether there were anti-β1-AR-ECI-antibodies in DCM patients involved in this study, we added peptide corresponding to the sequence of the 1st (β1-AR-ECI) as negative control, and found that the supernatant produced by incubating β1-AA-positive IgG with β1-AR-ECI still promoted CD3+T lymphocytes proliferation (Fig. S7A).