The idea behind gene therapy is simple enough. Just stick some genes into a virus and inject it into a person and the virus will do what viruses do and insert the genes into his cells. The reality, of course, is not so clean.
The first clinical human trial of gene therapy resulted in one death from an autoimmune reaction within days of the procedure and multiple cases of leukemia years later.
Naturally, a lot of science fiction treats gene therapy much less seriously.
Subtrope of LEGO Genetics
Live Action TV
- In Transmetropolitan getting a new "trait" is as simple as taking a pill. For instance Spider has a bag full of anti-cancer genes in his bathroom so he and his assistants can smoke like chimneys.
- In the second episode of Stargate Atlantis Dr. Beckitt developed a retrovirus that could give any human the genetic marker required to use Ancient technology. A shot and a few hours and they were ready to fly a puddlejumper. However his attempts to create a Synthetic Plague that turned Wraiths into humans were much less successful, at best it was temporary, and the first version instead turned them into bipedal Iratus Bugs.
- In the Star Trek: The Next Generation episode "Genesis" Dr. Crusher gives Lt. Barclay a shot to activate a dormant gene, which inadvertently activates all his dormant genes and causes them to spread by air, which in turn makes everyone on the ship "devolve" into a previous incarnation of their species history (Riker turns into a caveman, Worf into a cave-Klingon, Troi into a fish, Barclay into a spider for some reason, Data's cat into an iguana, etc.).
- Star Trek: Voyager episode "Favorite Son". Harry Kim is changed into a Taresian by a virus that implanted Taresian genes into his body, with the genes then re-writing his DNA. The ship's holographic doctor is able to extract the alien DNA and return him to normal.
- In GURPS Transhuman Space gene therapy is mostly accomplished via Nano Machines, though the grossest physical change they can do is give you fur or scales.
- Warhammer 40K
- Averted with the Tyranids; instead of reconfiguring a creature's various biomorphs it gets dissolved at a reclamation pool and a new one spawned with the right weapons.
- Played straight with Tyranid genestealers. As infiltration units, they first infect hosts with a small bundle of genetic material that doesn't mutate their bodies, only making them subservient to the Hive Mind. As infected organisms breed, the new generation of genestealers begin to show more and more mutations (though they can still pass as their host species) until the fifth generation, which are 100% purestrains.
- Averted with the Space Marines: the standard procedure requires inserting the various implants and organs over a long period of adaptation beginning in adolescence, and even then it is not always successful. There have been very few cases of adults surviving the process, but most of them died painfully.
- Played straight by the Kroot: their species is somehow able to extract useful genetic material from what they eat, and the more they eat of it, the more traits they acquire (eating birds results in lighter Kroot with limited gliding ability, quadrupeds into Kroothounds, etc.). Their leaders, called shapers, are able to analyze the DNA by tasting it and direct their warriors whether or not to eat something.
- GURPS Space Adventures, adventure "Rebirth". A genetic virus called Proteus can slowly change a human being into an alien.
- Dark Conspiracy. The Darktek supplement had Empathic Viral Mutators, a virus that could change the victim into another creature over a period of 48 hours.
- Plasmids in Bioshock, walk up to a vending machine, select your genes, and seconds later your hands can shoot lightning or bees or something.
- Starcraft. The Zerg's upgrades are basically retrofitted onto them, ranging fom sharper claws and tougher hides to extra organs and symbiotes.
- Averted in Metal Gear Solid, where access to the corpse of Big Boss (the Metal Gear series' Big Bad) was one of the rogue Foxhound unit's demands. They needed it to cure the side effects of failed gene therapy based on his DNA.
- Resident Evil has a few examples.
- The T-Virus is capable of mutating a person into a zombie. Sometimes this is plausible to a point (it takes days for the infection to take hold and only really seems to make a person's body rot), other times less so (people mutate in hours or minutes). Then any realism goes straight out of the window when you find out about zombies who mutate into Lickers, zombies coming back to life again as CrimsonHeads or the small amount of people who become Tyrants.
- The G-Virus from the second game was able to mutate William Birkin into a huge monster over the course of a day with a simple injection in the arm.
- The unnamed virus Albert Wesker injected himself with to fake his death in the first game somehow gave him superhuman speed and strength (and lizard-like eyes), all for the low, low price of going into a coma for a while.
- The "Veronica" strain of the T-Virus from Resident Evil: Code: Veronica quickly mutated Ashford Sr. and Steve into huge (and mindless) monsters. Alexia Ashford was able to mutate in a more controlled fashion by putting herself on ice for several years.
- Resident Evil 6 featured a strain of the virus that not only did the usual "allow this important villain to mutate into a boss" routine, but also made it possible to transform them into a copy of another person.
- One episode of Family Guy had Peter participating in a genetic research study where they would inject him with, say, a "squirrel gene" and he'd immediately transform into a squirrel-man for a period of time.
- In the world of Batman Beyond "splicing" is used to add animal traits to people. It's just a simple injection and takes (at most) a minute to take effect.
- In Blade Runner Roy suggests several possible ways to fix the Replicants' preprogrammed death with his creator Tyrell. He shoots them all down as they cause tumors or immune reactions.
- In Shadowrun gene therapy involves a couple months suspended in a tank of fluid while nanites or viruses alter your genome. And there's a significant chance of complications like cancer or in rare cases SURGE. And it always costs Essence.
- Averted in Genocide Man, it's stated that even under the most carefully controlled conditions gene therapy has a 1% death rate. And the Guyaquil plague was a contagious gene therapy package that killed nearly a billion people.
- Subverted in The Last Days of FOXHOUND (which is a Perspective Flip of the events leading up to the first Metal Gear Solid mentioned above). Naomi admits that there's a fair chance that the therapy might well just turn all the subjects into drooling vegetables. In the end, the soldiers don't get anything out of it except the canon gene degeneration.