Several of my children, in the summer before they began kindergarten, participated in a program called “safety city.” Among the ditties that seem destined to stick in my head forever is one they learned there:
The traffic light you see ahead
is sometimes green and sometimes red.
The red on top means “stop, stop, stop.”
The green below means “go, go, go.”
Noticeably missing from this little piece of poetic instruction is the yellow light. Perhaps one has to be a little older to learn how to deal with it. We’re supposed to stop when the light turns yellow, but sometimes we’re already quite near the intersection. So then we tend to treat it like a warning sign and just “proceed with caution.”
I’m pretty sure I never thought much about the yellow light until I learned to drive. In the early stages of my driving experience I heeded it religiously. I never entered an intersection on a yellow light. I think I even slowed just slightly (a bad idea actually) as I approached an intersection, just in case the yellow light should suddenly appear. My approach was to proceed with caution.
Those days are gone. Now I mostly just proceed. Not only do I routinely enter intersections when the traffic light is yellow, I am likely to accelerate a bit as I approach, the better to proceed before the light turns red. To be sure, I do not run red lights. But over time, as life’s routines have accustomed me to intersections, the yellow has become less and less distinguishable from the green, even though in theory I am supposed to stop for it. And I suspect that my experience is not all that uncommon. Knowing that I don’t run red lights, I have a pretty good conscience about sailing through yellow ones.
I found myself thinking about yellow lights as I looked through the exhaustively detailed report, “Human Genome Editing: Science, Ethics, and Governance,” recently produced by an advisory group formed by the National Academy of Sciences and the National Academy of Medicine. In most ways the salient moral issues do not seem to me to have changed much from the last time I thought at length about these issues roughly a decade ago.
One thing, however, has changed considerably—namely, the development of what is called CRISPR/Cas9, a new method for “editing” the human genome. Attempts at gene therapy, although not terribly successful, have been around for some time. What CRISPR/Cas9 appears to offer, however, is an efficient and precise method for altering (both by addition and deletion) an organism’s genetic material. We stand on the brink of an age in which our capacity to modify the human genome may increase enormously. And not surprisingly scientists are eager to proceed with gene-editing research.
What sorts of research are under consideration or, at least, possible? Most obviously, basic laboratory research that does not, at least for now, attempt clinical applications. In addition to increasing our understanding of human biology generally, such research could increase our understanding of important areas of medicine, positioning us for future attempts at clinical applications. Researchers could increase their understanding of fertility and reproduction, perhaps opening doors for greater success with in-vitro fertilization (IVF) and related techniques. They might create disease models for study, with the hope of one day developing new approaches to treatment.
Still more dramatically—and the issue that received the most notice in news stories about the Academies’ report—researchers might develop further the capacity to do what the report calls “heritable germline editing.” Most cells in the body are known as somatic cells (from the Greek word soma, meaning “body”). These cells are differentiated to form the body’s organs, tissues, skin, and bones. Somatic cells may undergo change (through mutation, for instance), but those changes die when the individual dies. They are not passed on to future generations. By contrast, germ cells, which give rise to sperm and eggs, are not differentiated into the various parts of the body, and changes in the germline could be inherited by future generations. Hence, to “edit” the germline is to exercise power not only over an individual patient but also over descendants of that individual into an indefinite future.
In principle, somatic-cell research aimed at developing possible treatments for disease is not controversial. It is simply an extension of medicine’s attempt to treat patients—to cure or ameliorate disease and debilitating injury. Genetic therapies might one day enable us to treat inherited genetic diseases such as cystic fibrosis or Tay-Sachs. Research in what is called regenerative medicine may increase our capacity to help those suffering from Parkinson’s or Alzheimer’s, or to produce sheets of skin for burn victims, or to replace heart muscle. To be sure, many things can go awry—and sometimes have—when we proceed from somatic-cell research to clinical attempts at genetic therapy. But at least for any work supported by federal government funding, we have in place a number of regulatory mechanisms aimed at ensuring, as much as possible, that attempts at genetic therapy will take place only after their safety has been rigorously studied and we have reason to believe the hoped-for benefits of the therapy are greater than its risks. In general, the report of the Academies regards this current regulatory structure as adequate for somatic-cell research, and there seems little reason to disagree.