Edit the Human Genome–Or Not?

Back to the future—Award-winning scientists propose to ban their own Franken-genetics?  Jennifer Doudna, bacterial molecular biologist, called the meeting, along with Nobel winners David Baltimore and Paul Berg. Back in 1975, Berg’s Asilomar conference famously called for banning certain kinds of “recombinant DNA,” the splicing of DNA from one species into another. A long time since then, we’ve gotten used to multiply spliced bacteria making antibiotics, and mice glowing with Green Fluorescent Protein from a squid.

But altering human embryos remained relegated to science fiction. Until now. We how have techniques that can effectively (if imperfectly) edit the genomes of various mammals, including mice and human embryos. The most effective of these “editing” techniques is called CRISPR (clustered regularly interspaced short palindromic repeats). CRISPR was presented by Ultraphyte recently as a potential means of cutting HIV genomes out of the chromosomes of infected patients.

As shown in this Wikipedia diagram, CRISPR in nature is a mechanism by which bacteria obtain bits of DNA from invading bacteriophages (viruses) and use them to store information against the next time–A bacterial immune system. The mechanism requires inserting the viral DNA into the bacterial chromosome, then making an RNA copy next time, which combines with a protein complex to snip the invading viral DNA.

But the key part for editing is the CAS protein complex, which acquires the viral DNA and splices it into the host DNA. This mechanism turns out to work for any DNA, even mouse or human. Already, many applications are in progress for treating  human diseases by editing DNA of somatic cells (body cells, not inherited). The difference is that if the technique gets too efficient, we’ll use it on embryos, to prevent disease and select baby’s eye color.

I wonder, though, if the battle isn’t lost already. Science fiction writers have threatened to change baby’s eye color for maybe a century now, and the threat’s getting old. The very terms used–“editing,” in place of recombination–makes the prospect hard to get worked up about. What’s a little “editing”?

Back in the 50s, when natural human recombination was a serious business (Catholics didn’t marry Protestants) the odd things bacteria did were labeled “illegitimate recombination.” The horror of “illegitimate” required no explanation. It took several decades for scientists even to admit humans (and our viruses) do that sort of thing. Today, bacteria have “pangenomes” (access to infinite genes) and young people fashionably call themselves “pansexual” (attracted to infinite genders).

I know the consequences should concern us, but until we come up with more concrete issues than “editing” and “limits of our knowledge,” parents and their doctors are going to press ahead with clinical trials. Mitochondrial transplant (involving triparental embryos) is already out the door, as is embryo selection to save the life of a sibling. Anything to save the life of a child.