PKP2 and cardiomyopathy: ,43 Moreover, an increased expression level of phospho-H2A.X variant histone (pH2AFX), a marker of DSBs, in cardiac myocytes has been reported in a mouse model of lamin A (LMNA), TMEM43, and plakophilin 2 cardiomyopathy.41, 42, 43,54 Collectively, the data support the presence of DNA damage, including strand breaks in cardiomyopathies not only in cardiac myocytes but also in cardiac fibroblasts in multiple genetic models and human hearts.