With this power at hand, old questions about playing God, making designer babies, and ushering in dystopian Brave New Worlds of genetic haves and have-nots, take on fresh urgency. These same leitmotifs are trotted out with every new wave of genetic technology—IVF, cloning, stem-cell therapies, mitochondrial-replacement therapy—but some say they are more pertinent than ever. “In the past, it’s been simple for scientists to dismiss these possibilities,” said Robin Lovell-Badge from The Francis Crick Institute. “But we’re rapidly getting to the point where we can no longer deny them.”
This turning point came in April, when a team led by Junjiu Huang from Sun Yat-sen University, announced that they had edited human embryos with CRISPR, tweaking the faulty gene behind an inherited disease called beta-thalassaemia. (The team used inviable embryos that could never have developed into an actual person.) The research caught the world off guard. In the U.S., it could not have been done, at least not with federal funding. In the U.K., it’s permissible with a license, as long as embryos are younger than 14 days.
In response, some scientists have called for a moratorium on any kind of human germline editing until the world can assess the safety of CRISPR and other gene-editing tools, discuss the social consequences of such technologies, and draw up clear ethical guidelines and regulations.
Hence the summit. But the delegates spent much of the first day wrestling with a more subtle question: Even if we could edit human genes safely and precisely, why would we do so?
If you’re looking to edit genes in actual people, the most obvious application is to treat diseases. A month ago, doctors cured a girl with untreatable leukaemia by removing immune cells, editing them so they’d go after cancer cells while also resisting a chemotherapy drug, and then injecting them back into her. Other teams are trying to remove cells from people with HIV, deleting a gene that the virus needs to stage its invasions, and injecting them back in. These are examples of somatic cell therapy—they affect cells that stay within a person’s body and die with them.
It’s far more controversial to edit the human germline—that is, genes of sperm, eggs, or early embryos. These modifications wouldn’t just affect one individual but also their descendants. They would cascade down generations, potentially altering the course of human heredity.
Germline modifications would make the biggest difference in cases of severe inherited diseases, like cystic fibrosis, Huntington’s disease, or Tay-Sachs disease, which all cause debilitating symptoms, carry a poor prognosis, and are caused by mutations in single genes. In an era with safe, efficient gene-editing, these conditions could be entirely preventable. “I’m the mother of a child who died because of a fetal birth defect,” said Sarah Gray from the American Association of Tissue Banks to one group of panelists. “He was six days old and he suffered every day. He had seizures every day. If you have the skills and the knowledge to fix these diseases, then frickin’ do it.”