Engineering the Perfect Baby

baby bubble

Scientists are developing ways to edit the DNA of tomorrow’s children. Should they stop before it’s too late?

 If anyone had devised a way to create a genetically engineered baby, I figured George Church would know about it.

At his labyrinthine laboratory on the Harvard Medical School campus, you can find researchers giving E. Coli a novel genetic code never seen in nature. Around another bend, others are carrying out a plan to use DNA engineering to resurrect the woolly mammoth. His lab, Church likes to say, is the center of a new technological genesis—one in which man rebuilds creation to suit himself.

When I visited the lab last time, Church proposed that I speak to a young postdoctoral scientist named Luhan Yang. A Harvard recruit from Beijing, she’d been a key player in developing a powerful new technology for editing DNA, called CRISPR-Cas9. With Church, Yang had founded a small biotechnology company to engineer the genomes of pigs and cattle, sliding in beneficial genes and editing away bad ones.

As I listened to Yang, I waited for a chance to ask my real questions: Can any of this be done to human beings? Can we improve the human gene pool? The position of much of mainstream science has been that such meddling would be unsafe, irresponsible, and even impossible. But Yang didn’t hesitate. Yes, of course, she said. In fact, the Harvard laboratory had a project under way to determine how it could be achieved. She flipped open her laptop to a PowerPoint slide titled “Germline Editing Meeting.”

Here it was: a technical proposal to alter human heredity. “Germ line” is biologists’ jargon for the egg and sperm, which combine to form an embryo. By editing the DNA of these cells or the embryo itself, it could be possible to correct disease genes and pass those genetic fixes on to future generations. Such a technology could be used to rid families of scourges like cystic fibrosis. It might also be possible to install genes that offer lifelong protection against infection, Alzheimer’s, and, Yang told me, maybe the effects of aging. Such history-making medical advances could be as important to this century as vaccines were to the last.

That’s the promise. The fear is that germ-line engineering is a path toward a dystopia of superpeople and designer babies for those who can afford it. Want a child with blue eyes and blond hair? Why not design a highly intelligent group of people who could be tomorrow’s leaders and scientists?

Just three years after its initial development, CRISPR technology is already widely used by biologists as a kind of search-and-replace tool to alter DNA, even down to the level of a single letter. It’s so precise that it’s expected to turn into a promising new approach for gene therapy in people with devastating illnesses. The idea is that physicians could directly correct a faulty gene, say, in the blood cells of a patient with sickle-cell anemia (see “Genome Surgery”). But that kind of gene therapy wouldn’t affect germ cells, and the changes in the DNA wouldn’t get passed to future generations.

In contrast, the genetic changes created by germ-line engineering would be passed on, and that’s what has made the idea seem so objectionable. So far, caution and ethical concerns have had the upper hand. A dozen countries, not including the United States, have banned germ-line engineering, and scientific societies have unanimously concluded that it would be too risky to do. The European Union’s convention on human rights and biomedicine says tampering with the gene pool would be a crime against “human dignity” and human rights.

But all these declarations were made before it was actually feasible to precisely engineer the germ line. Now, with CRISPR, it is possible.

The experiment Yang described, though not simple, would go like this: The researchers hoped to obtain, from a hospital in New York, the ovaries of a woman undergoing surgery for ovarian cancer caused by a mutation in a gene called BRCA1. Working with another Harvard laboratory, that of antiaging specialist David Sinclair, they would extract immature egg cells that could be coaxed to grow and divide in the laboratory. Yang would use CRISPR in these cells to correct the DNA of the BRCA1 gene. They would try to create a viable egg without the genetic error that caused the woman’s cancer.

Yang would later tell me that she dropped out of the project not long after we spoke. Yet it remained difficult to know if the experiment she described was occurring, canceled, or awaiting publication. Sinclair said that a collaboration between the two labs was ongoing, but then, like several other scientists whom I’d asked about germ-line engineering, he stopped replying to my e-mails.

Regardless of the fate of that particular experiment, human germ-line engineering has become a burgeoning research concept. At least three other centers in the United States are working on it, as are scientists in China, in the U.K., and at a biotechnology company called OvaScience, based in Cambridge, Massachusetts, that boasts some of the world’s leading fertility doctors on its advisory board.