Earlier studies also showed that heart-restricted deletion of Tfam led to DCM and conduction blockade (Wang et al., 1999), whereas cardiac Tfam overexpression not only increased mtDNA copy number (Watanabe et al., 2011; Ikeda et al., 2015), but also was cardioprotective in the setting of chronic volume-overload (Ikeda et al., 2015). Here, TFAM is linked to familial dilated cardiomyopathy.