XRCC1 and heart failure: Echocardiographic analysis revealed mild cardiac dysfunction in Xrcc1αMHC-Cremice (Supplementary Fig. 4d), but the mice showed no overt signs of heart failure such as tachypnea, weight loss and pleural effusions beyond 1-year follow-up (Supplementary Fig. 4e), suggesting that deletion of Xrcc1 in cardiomyocytes is not sufficient to induce heart failure.