It has been proposed that up to 90% of human cancers reactivate telomerase via multiple genetic and epigenetic mechanisms that include TERT and TERC gene amplification, TERT promoter (TERTp) mutation and methylation, genomic rearrangement of TERT (e.g., insertion of active enhancers close to the TERT gene), post-transcriptional regulation by microRNAs, and alternative splicing of the TERT gene [67,68]. The gene discussed is TERT; the disease is cancer.