KDM8 and familial dilated cardiomyopathy: KDM8 maintains an active mitochondrial gene network by repressing TBX15, thus preventing DCM and lethal HF.80 KDM8 was down-regulated in human hearts affected by DCM, and higher TBX15 expression was correlated with the down-regulation of genes encoding mitochondrial proteins, suggesting that epigenetic dysregulation of metabolic gene networks, mediated by the KDM8-TBX15 axis, could initiate myocardial deterioration towards HF.80