A group of scientists at the Children’s Hospital of Philadelphia have recently used genome editing to make hemophilia B in mice less severe. Hemophilia B is an inherited genetic disorder that prevents blood from clotting correctly. The most severe forms of hemophilia, where less than 1% of the normal clotting factors in blood are present, can cause spontaneous internal bleeding around the joints even without suffering traumatic injury. Additionally, patients may bleed spontaneously from the nose or gums; a severe problem when the blood fails to clot and the bleeding doesn’t stop. Traditional treatments for hemophilia include injections of harvested or synthetic clotting factors or pills that include synthetic factors.
By introducing an enzyme into the mice, Dr. Katherine High and crew have rewritten the DNA of mice, causing the mice to produce more of the needed clotting factors. After injection, the virus makes its way to the mouse’s liver, and the enzyme cuts out the faulty gene in the cellular DNA. By injecting healthy copies of DNA into the mouse, the faulty DNA is replaced during the body’s normal repair process, and the mouse begins to produce more of the clotting factor. Because the DNA has been rewritten, these cells then continue to produce more of the clotting factor, reducing or eliminating the need for repeated injections or pills. Although this is only the first time genetic rewriting has been successfully used on a living animal, Dr. High and crew have increased the clotting factor in these mice from 1% to 5%; enough to change the severity of the mice’s hemophilia from “severe” to “moderate” or “mild” (5% is the accepted
line between mild and moderate hemophilia.) The additional clotting factors lessen the likelihood of spontaneous bleeding at the joints, and patients generally only bleed excessively during surgery or after injury. Dr. High and her team hope to increase the efficiency of the genetic treatment in the future, and apply it to other genetic diseases and HIV.
I’m no genetic scientist, so I’m unsure why only 4%-5% of the DNA would be successfully rewritten. Maybe this is Hollywood talking (I’m looking at you, Resident Evil and I Am Legend), but I’m also a little leery about rewriting DNA. Unlike pharmaceuticals that work their way through the body and are then expelled, one of the main benefits (and potential dangers) of genetic rewriting is that the alterations are permanent. I’m not suggesting that scientists ought not use viral vectors to alter DNA, or denying the efficacy and benefits of editing genomes. Indeed, I think that DNA rewriting is our best shot at curing many of the diseases that currently plague people, and offers the most immediate shot at meaningful enhancement to longevity and abilities. Ray Kurzweil, in The Singularity Is Near, called this type of procedure “the holy grail of genetic bio-engineering,” and I’m certainly not going to argue with Ray. Still, even though this on-the-fly rewriting of DNA in living organisms isn’t yet ready for human trials, I’d like to see scientists begin to educate the public on the relative safety of this sort of procedure. At the very least, some reassurance that an accidental zombie apocalypse only happens in the movies would be nice.
Assuming that this sort of treatment -is- safe, however, genetic rewriting offers a number of exciting opportunities. While ‘coding out’ genetic disorders ought probably be at the top of the to-do list, by rewriting DNA we can ‘code in’ any number of beneficial enhancements to ourselves, from more robust immune systems that can fight off bacterial and viral infection not susceptible to this sort of DNA rewriting cure to more frivolous applications like changing eye and hair color. Because all aspects of the human body are dictated by our DNA, rewriting that DNA offers us the ability to enhance ourselves in any way that we know how to encode for. We could not only tweak our own genetic code and alter it by copying parts of other humans with better genes, but potentially integrate superior attributes of other animals that are, themselves, determined by their DNA. Limited only by our own ingenuity and understanding, we ought to be able to enhance ourselves in any way that nature allows.
Ultimately, I still thing that mechanical implants and engineering will surpass even the vast opportunity afforded by genetic rewriting because mechanical engineering is not limited to the best of nature’s creativity. Very strong bones are certainly beneficial, but calcium cannot hope to compete with titanium and other alloys. Immune systems can do a great job of maintaining our bodies, but eventually nanobots will overcome even the most robust solutions nature allows. All that said, we are rewriting DNA now, and still in the very early stages of creating nano-scale engineering. Until engineering catches up with genetics, this seems to be our best chance at meaningful enhancement in the near future.