Interestingly, Ckmm‐Cre+/−;Ercc1−/fl mice showed significant fibrotic changes in pulmonary vasculature at 6 months (Figure 2e, right panels), commonly seen in cardiomyopathy (Lijima et al., 1993) and consistent with our observation that mutant animals displayed dyspnea prior to sudden death (Videos S1 and S2). The gene discussed is CKM; the disease is cardiomyopathy.