For example, carcinomas with isocitrate dehydrogenase 1 (IDH1) mutations, such as gliomas and sarcomas, tend to downregulate NAPRT levels through hypermethylation of the NAPRT promoter, thereby blocking the NA–NAPRT pathway, which makes them dependent on NAMPT for NAD replenishment [53]. Here, IDH1 is linked to central nervous system cancer.