CD4 and familial dilated cardiomyopathy: The lymphocytic component has been validated by immunohistochemistry as being predominantly T-cell (CD3 +), while single-cell sequencing from explanted DCM hearts revealed that the proportion of exhausted/cytotoxic CD8 + and pro-inflammatory CD4 + T-cell subtypes [5] A large amount of evidence suggests that inflammation and immune dysregulation play a causative role in DCM as either a primary triggering factor or as a pivotal disease accelerator [6].