NMRK2 and familial dilated cardiomyopathy: In the murine and human failing heart biopsies, the observed reduction in NAD+ homeostasis and the activation of nicotinamide riboside kinase 2 (NMRK2 kinase), an enzyme involved in the phosphorylation of nicotinamide riboside precursor, was considered as events of DCM leading to heart failure [36].