Designer Babies

What if parents could customize a baby much like choosing a car, selecting attributes like eye color, size, and the ability to run fast?

It sounds like science fiction, but the reality might not be as far off as you think.

In November, He Jiankui, a researcher in China, upended the world of genetics by announcing the first gene-edited babies; he claimed to have altered a gene in the embryos of a pair of twin girls to make them resistant to H.I.V., the virus that causes AIDS.

His announcement has set off an intense debate among scientists, many of whom see gene editing as a potentially promising avenue for fighting disease but worry that the technology is outpacing considerations of the ethical questions involved in altering human DNA.

“Should such epic scientific misadventures proceed,” says Francis Collins, director of the National Institutes of Health in Bethesda, Maryland, “a technology with enormous promise for prevention and treatment of disease will be overshadowed by justifiable public outrage, fear, and disgust.”

Scientists have contemplated changing human genes ever since the structure of the DNA molecule was discovered in 1953 (see “Genetic Breakthroughs”). But the invention of a powerful gene-editing technique called Crispr in 2012 sparked a scientific revolution, allowing researchers to edit DNA with unprecedented ease and precision. It has already been used to change some animals’ DNA, including that of pigs (making them immune to a virus) and salmon (so they grow faster).

What if parents could customize a baby much like choosing a car? Maybe they’d be able to select certain traits, like eye color, size, and the ability to run fast.

It sounds like science fiction, but the reality might not be as far off as you think.

In November, He Jiankui, a researcher in China, announced the first gene-edited babies. The news upended the world of genetics. He claimed to have altered a gene in the embryos of a pair of twin girls. The change aimed to make the twins resistant to H.I.V. That’s the virus that causes AIDS.

His announcement has set off an intense debate among scientists. Many of them see gene editing as a potentially promising way to fight disease. Still, they worry that the technology is outpacing considerations of the ethical questions involved in altering human DNA.

“Should such epic scientific misadventures proceed,” says Francis Collins, director of the National Institutes of Health in Bethesda, Maryland, “a technology with enormous promise for prevention and treatment of disease will be overshadowed by justifiable public outrage, fear, and disgust.”

The structure of the DNA molecule was discovered in 1953 (see “Genetic Breakthroughs”). Since then, scientists have contemplated changing human genes. Things changed in 2012, with the invention of a powerful gene-editing technique called Crispr. It sparked a scientific revolution. The technique allows researchers to edit DNA with unprecedented ease and precision. It has already been used to change some animals’ DNA. It’s helped make pigs immune to a virus and salmon grow faster.

But fearing the technology might be misused, many countries—including the United States—have since placed bans or restrictions on altering the DNA of human embryos. China doesn’t have a ban, but a group of 122 Chinese scientists issued a statement denouncing He’s experiment.

Despite the condemnation, however, many scientists still believe gene editing could provide health benefits to humans once safety concerns have been worked out. Genetic mutations are linked to about 10,000 medical conditions, including Huntington’s disease, some cancers, and some cases of Alzheimer’s disease. If scientists could correct those mutations, it would ensure that no future family members would inherit them.

“If you have a way to help families not have a diseased child, then it would be unethical not to do it,” says Robin Lovell-Badge, a professor of genetics and embryology at the Francis Crick Institute in London. 

But many countries, including the United States, fear the technology might be misused. That’s why they’ve placed bans or restrictions on altering the DNA of human embryos. China doesn’t have a ban, but a group of 122 Chinese scientists issued a statement denouncing He’s experiment.

Despite the backlash, many scientists still believe gene editing could offer health benefits to humans once safety concerns have been worked out. Genetic mutations are linked to about 10,000 medical conditions. These include Huntington’s disease, some cancers, and some cases of Alzheimer’s disease. If scientists could correct those mutations, it would ensure that no future family members would inherit them.

“If you have a way to help families not have a diseased child, then it would be unethical not to do it,” says Robin Lovell-Badge, a professor of genetics and embryology at the Francis Crick Institute in London. 

But there are still major concerns about manipulating human DNA. The first is safety: So far, most attempts to edit human embryos in lab dishes have resulted in errors, such as the accidental altering of other genes. Research suggests that He’s study might have inadvertently changed the twins’ brains, for example.

Another issue is that when an embryo is edited, those changes are passed on to subsequent generations—meaning they will affect not just a single baby, but all of the baby’s descendants too. And that, scientists agree, makes gene editing a serious undertaking that must be done with great care and deliberation, if at all.

Finally, even if safety concerns are addressed, where should the gene-editing line be drawn? Should parents be able to create so-called designer babies, with all the traits they desire and none of the traits they don’t want?

“We could all too easily find ourselves in a world where some people’s children are considered biologically superior to the rest of us,” says Marcy Darnovsky, executive director of the Center for Genetics and Society.

But there are still major concerns about manipulating human DNA.

The first is safety. So far, most attempts to edit human embryos in lab dishes have resulted in errors. That includes mistakes such as the accidental altering of other genes. For example, research suggests that He’s study might have unintentionally changed the twins’ brains. 

Another issue is that when an embryo is edited, those changes are passed on to subsequent generations. That means any changes won’t just affect a single baby but all of the baby’s descendants too. And that, scientists agree, makes gene editing a serious undertaking. And it’s one that must be done with great care and deliberation, if at all.

Finally, even if safety concerns are addressed, where should the gene-editing line be drawn? Should parents be able to create so-called designer babies? Should they be able to choose all the traits they desire and none of the traits they don’t want?

“We could all too easily find ourselves in a world where some people’s children are considered biologically superior to the rest of us,” says Marcy Darnovsky, executive director of the Center for Genetics and Society.

At the moment, designer babies are still theoretical. In China, He changed only one gene to block H.I.V. infection—but creating an exceptional singing voice or a knack for basketball is far more complex. Even manipulating a straightforward physical characteristic would be tricky; scientists estimate height, for example, is influenced by as many as 93,000 genetic variations.

“Right now, we know nothing about genetic enhancement,” says Hank Greely of the Center for Law and the Biosciences at Stanford. “We’re never going to be able to say, honestly, ‘This embryo looks like a 1550 on the two-part SAT.’”

At the moment, designer babies are still theoretical. In China, He changed only one gene to block H.I.V. infection. But creating an exceptional singing voice or a knack for basketball is far more complex. Even manipulating a straightforward physical characteristic would be tricky. For example, scientists estimate that as many as 93,000 genetic variations influence height.

“Right now, we know nothing about genetic enhancement,” says Hank Greely of the Center for Law and the Biosciences at Stanford. “We’re never going to be able to say, honestly, ‘This embryo looks like a 1550 on the two-part SAT.’”

Ultimately, genetic engineering doesn’t have to be all or nothing. In 2017, the National Academies of Sciences, Engineering, and Medicine in Washington, D.C., concluded that editing human embryos should be allowed for correcting serious genetic disorders when there are no other alternatives; when there is good evidence that the benefits would outweigh the risks; and when there is a plan in place to study the gene-edited children.

Scientists are currently debating safeguards that would prevent dangerous experiments from happening while still encouraging solid research.

“An outright ban never helps,” says Shoukhrat Mitalipov, director of the Center for Embryonic Cell and Gene Therapy at Oregon Health and Science University. He hopes that the work of responsible researchers will help build public support for gene editing.

“We have to bring in more young scientists,” he says. “I think this is where the future will go.”

Ultimately, genetic engineering doesn’t have to be all or nothing. In 2017, the National Academies of Sciences, Engineering, and Medicine in Washington, D.C., offered some guidelines for editing human embryos. They said it should be allowed for correcting serious genetic disorders when there are no other alternatives; when there is good evidence that the benefits would outweigh the risks; and when there is a plan in place to study the gene-edited children.

Scientists are currently debating safeguards that would prevent dangerous experiments from happening. But they still want to encourage solid research.

“An outright ban never helps,” says Shoukhrat Mitalipov, director of the Center for Embryonic Cell and Gene Therapy at Oregon Health and Science University. He hopes that the work of responsible researchers will help build public support for gene editing.

“We have to bring in more young scientists,” he says. “I think this is where the future will go.”

With reporting by Pam Belluck, Gina Kolata, and Sui-Lee Wee of The New York Times.

With reporting by Pam Belluck, Gina Kolata, and Sui-Lee Wee of The New York Times.