STUB1 and familial dilated cardiomyopathy: Furthermore, in support of a potential link between FBXO32 and DCM in this family, other cardiac ubiquitin ligases (MuRF1, MuRF2, MuRF3, CHIP, MDM2) have also been implicated in the pathogenesis of cardiac hypertrophy, atrophy, and ischemia reperfusion injury.5 Recently, mutations in the cardiac ubiquitin ligase TRIM63, which encodes MuRF1, have been identified in patients with familial hypertrophic CMP [26].