NPPB and familial dilated cardiomyopathy: Tang et al. [139] demonstrated that a decrease in the proportion of B1 cells is strongly correlated with a reduction in left ventricular ejection fraction (LVEF), elevated NT-proBNP levels, and increased levels of β1-AR autoantibodies, indicating that a decline in B1 cell numbers can exacerbate cardiac dysfunction and the development of heart failure in individuals with DCM.