The origin of oxidized guanine resolves the puzzle of oxidation-induced telomere-length alterations

Although oxidative stress has long been considered to be a major factor contributing to telomere shortening, recent work has established that oxidative stress and DNA damage are linked to telomere lengthening. Now, Opresko and colleagues resolve this apparent discrepancy by showing that differential modulation of telomerase activity depends on the origin of a common oxidative guanine lesion.