Gene dreams

Cutting-edge microbiology was an election issue in 2004, when presidential candidate John Kerry used Michael J. Fox and the late Christopher Reeve as object lessons for his proposal to lift federal “bans” (actually, restrictions on federal money) from embryonic stem cell research. Since then, experimentation on human embryos has not been much of a political football, perhaps because it has produced no significant results. It’s time to open the conversation again, in light of the new technology storming the frontier of genetic research all over the world.

The CRISPR-Cas9 technique originated in the observation that certain bacteria use a unique system of protection from viral invasions. The bacteria copy the DNA of those nasty viruses in single-cell strands, sometimes described as molecular “wanted posters,” in order to recognize and dispatch an invader. These sequences were named Clustered Regularly Interspaced Short Palindromic Repeats, or CRISPRs. Studying the virus-fighting system further, scientists discovered how CRISPR-associated (Cas) proteins, particularly Cas9, combined with the molecules to produce RNA (the “transcriber” molecule) that can attach to the offending viral DNA and disable it.

In 2012, geneticists working in two separate labs discovered how, using the CRISPR-Cas9 technique, “guide RNA” can be created and targeted to specific areas on the genome—say, a gene related to cystic fibrosis in humans. The RNA/Cas9 compound attaches to those particular gene sequences and removes them, thus wiping out undesirable traits in the parent cell’s progeny.

Technology aimed at the tiny human embryo is a subtle knife whittling at the joints and marrow of who we are and how we think of ourselves.

In just four years, experiments on plants, zebra fish, mice, and monkeys have proven that material can be removed from and added to an organism’s genome almost at will. The “editing” technique is not only precise, but relatively inexpensive. It can be done in an upscale clinic—the equivalent, according to one reporter, of a home brewery. The possibilities are wonderful: eliminating Duchenne muscular dystrophy and sickle cell anemia, correcting birth defects before birth—even mutating or eliminating mosquitoes that spread diseases.

And the possibilities are dreadful: Behind every report of scientific good news lurks potential bad news. Last year the National Institutes of Health, among other organizations, recommended a moratorium on CRISPR research on human embryos, even while scientists in China charged ahead with it. This August, the NIH reversed course and signaled pending approval of human/animal hybrids. In Sweden, biologist Fredrik Lanner has begun editing the genes of healthy human embryos, which are afterward destroyed.

“I really, of course, stand against any sort of thoughts that one should use this to design designer babies or enhance for aesthetic purposes,” Lanner told NPR. He seems not to realize that today’s of course not easily becomes tomorrow’s moral imperative. In the United States, there are no restrictions on privately owned in vitro fertilization (IVF) labs to do whatever they can with whatever they get. Any clinic, at this moment, can purchase “cassettes” of guide RNA to target specific genes, and it’s at least theoretically possible that couples with limitless funds and hubris may design their own progeny before long.

“Progress” marched on: In Japan, scientists have manipulated rodent skin cells into viable egg cells, clearing the way for mass cloning (see "Eggs and ethics" in this issue). Why isn’t this brave new world an election issue? Maybe because, while we’re busy arguing about the candidates’ moral and physical fitness to lead, we’ve neglected to consider where they might lead us to. Technology aimed at the tiny human embryo is a subtle knife whittling at the joints and marrow of who we are and how we think of ourselves. As Time reported last February, “The ability to manipulate the human genome with such precision and relative ease raises inevitable questions about how far this intervention can and should go.” Where technology is concerned, it seems that can always cancels out should.

With one hand, CRISPR and related therapies hold out hope for avoiding, treating, or wiping out degenerative diseases. With the other hand they offer a plausible dream for “transhumanists” who can’t wait to discard our outdated bodies for the sleek, seamless ones produced by a new and improved genome. But what scientist can edit out the sin gene?

Email jcheaney@wng.org