In contrast, expression of the gene encoding nicotine riboside kinase 2 (Nmrk2), which converts nicotine riboside to the NAD+ precursor nicotine mononucleotide, was upregulated in hearts at all stages of DCM (Fig. 3d and Extended Data Fig. 6). The gene discussed is NMRK2; the disease is familial dilated cardiomyopathy.