Temporal RNA
From Memory Alpha, the free Star Trek reference.
Temporal RNA are artificial base pair sequences which can be built into the RNA of genetically engineered organisms, to allow the aging of the host organism to be accelerated at a certain point. Temporal RNA sequences were incorporated into Shinzon, a clone of Jean-Luc Picard, so that his age could be advanced to match that of the real Picard. However, those sequences were never activated, resulting in the fatal degradation of Shinzon's genetic structure. Shinzon would have required a complete transfusion from a genetically compatible donor (Picard) to correct the problem. (Star Trek Nemesis)
