The genetic and epigenetic mechanisms of telomerase activation in cancer include somatic telomerase reverse transcriptase (TERT) alterations, such as TERT promoter (TERTp) mutation, TERT amplification, TERT or TERTp structural variations, and TERTp hypermethylation, which induce the expression of TERT [6]. The gene discussed is TERT; the disease is cancer.