Telomeres, Telomerase, and Human Disease

Telomeres, the genetic segments that appear at a chromosome's ends, have been known since the 1930s to have special properties that protect these ends. They were first isolated in the 1970s and 1980s and shown to be made up of DNA repeats that, when transferred to the ends of artificial chromosomes in yeast, could protect them from degradation. At the same time, a newly discovered enzyme called telomerase was found to add telomere repeats to the ends of chromosomes with the use of a dedicated RNA template. This mechanism of telomere addition by telomerase solved the "end-replication problem" — the . . .