This approach successfully led to replacement of the mutant TERT allele with a wild-type allele in the SCaBER cancer cell line, which normally contains one wild-type and C124T mutant TERT allele, leading to a 40% to 50% reduction in telomerase activity, impairment of telomere elongation, and inhibition of cell growth compared to the parental cancer cell line. Here, TERT is linked to cancer.