News in Contect

A Moratorium on Gene Editing?

Leading biologists made front-page news last month by calling for a moratorium on the use of powerful new tools for editing the human genome. While these tools raise hopes of curing genetic diseases, they could also make genetic changes that would be capable of being passed on to future generations, raising a number of ethical questions. “The moratorium is a good idea,” writes Gregory Kaebnick in a commentary in Bioethics Forum, the blog of the Hastings Center Report. Kaebnick is a research scholar at The Hastings Center who studies ethical implications of biotechnology.

What is it? Gene editing is the capability of making genetic changes easily, inexpensively, and with great precision. “There have always been two big challenges confronting anyone who wants to edit the human genome: making the genetic changes correctly (getting them into cells and then into the genome at the right location) and making the correct genetic changes (actually achieving the results without accidentally creating new problems,” writes Kaebnick. One of the gene editing tools, called CRISPR/Cas9, “makes tremendous headway on the first problem,” he writes. But neither CRISPR/Cas9 nor the other new gene editing tool, called zinc-finger nucleases, can yet solve the second problem, that of identifying and making the correct genetic changes.

Why is it controversial? What prompted the scientists to call for a self-imposed moratorium on gene editing is that it could be used to alter human germline cells (sperm and egg cells and embryos), which means that whatever genetic changes were made could be inherited in perpetuity. The prospect of manipulating the human germline has raised ethical concerns ever since genetic engineering of animals began in the 1970’s. But what was merely a possibility has come closer to reality. CRISPR/Cas9 has been used to edit monkey embryos, resulting in the birth of monkeys with precise genetic mutations. As David Baltimore, a Nobel laureate and former president of the California Institute of Technology, told the New York Times, “You could exert control over human heredity with this technique, and that is why we are raising the issue.” Baltimore is one of a group of scientists calling for a moratorium on any attempt to use gene editing to alter the human germline for clinical purposes until its ethical, social, and legal implications are explored internationally. Another group seeks a moratorium on gene editing for both clinical and research uses.

News in context. Gene editing “does not have us right on the doorstep of editing the human genome,” Kaebnick says, “but it may well have us on the doorstep of some other very significant forms of genetic engineering,” such as modifications to microorganisms, animals, or plants. These raise concerns not mentioned in the recent news articles. Mosquitoes, for example, could be altered so that they no longer transmit malaria or dengue fever. But because it remains difficult to identify and make correct genetic changes, there is the risk (although it may be very slight) that altered mosquitoes “could be worse than the original in some ways,” he says. There are also unforeseen effects on the ecosystem. Given these uncertainties, Kaebnick supports a temporary moratorium both on editing the human germline and on applications of gene editing to other species, leaving time to study the implications before deciding which applications would pass muster. “These technologies could bring great benefits, but we need to do the necessary thinking and planning to make sure they do, he says.