Margaret Atwood's 2003 novel Oryx and Crake depicts the evolution and aftermath of a bioengineered global catastrophe. Whether Atwood at the time was privy to insider knowledge that genetic alteration would become easy to do and ubiquitous or whether she just thought it would make a good premise for a novel, I do not know.
What we have now, however, is a world moving ever forward toward what is being called the democratization of genetic engineering or biohacking for short. Anyone with a credit card and a mailing address can now order their own genetic engineering kit. Meanwhile, in major research laboratories around the world visits from awed reporters are bringing the possibility of fabulous advances in medicine to the attention of the public.
Some 6,000 diseases are thought to be linked to our genetic structure. Could these diseases not only be prevented in newly forming humans in utero, but also cured on the fly in fully fledged humans through means that alter their DNA? The preliminary answer is possibly.