LONDON/PARIS – In a landmark decision that some ethicists warn is a step down the path toward “designer babies,” Britain gave scientists approval Monday to conduct experiments in which they will try to edit the genes in human embryos.
The scientists won’t be creating babies — the modified embryos will be destroyed after seven days, and the new authorization requires their destruction within 14 days.
Gene editing is far more precise than conventional selective breeding or an earlier generation of genetic engineering techniques, and is already widely used to add desirable traits to food crops or livestock, and in lab animals for research on disease.
The goal of the newly authorized experiments in the U.K. is to better understand human development and thereby improve fertility treatments and prevent miscarriages, the scientists said.
The decision by Britain’s Human Fertilisation and Embryology Authority marks the first time a county’s national regulator has approved the technique. Permission isn’t explicitly required in many other countries, including the U.S. and China. The U.S. does not allow the use of federal funds for embryo modification, but there is no outright ban.
Gene editing involves deleting, repairing or replacing DNA inside living cells in a sort of biological cut-and-paste technique that scientists say could one day lead to treatments for conditions like HIV or inherited disorders such as muscular dystrophy and sickle cell disease.
The human genome consists of long strings of DNA made up of about 3 billion “base pairs” of the chemical “letters” A, T, G and C (adenine, thymine, guanine and cytosine) in a particular order. These comprise about 20,000 to 25,000 genes.
A team led by Kathy Niakan, an embryo and stem cell specialist at London’s new Francis Crick Institute, received the OK to use gene editing to analyze the first week of an embryo’s growth.
This research will “enhance our understanding of IVF (in vitro fertilization) success rates by looking at the very earliest stage of human development,” said Paul Nurse, director of the institute.
None of the embryos will be transferred into women in the study. They will be allowed to develop from a single cell to around 250 cells before they are destroyed.
Peter Braude, a retired professor of obstetrics and gynecology at King’s College London, said the mechanisms being investigated by Niakan and her colleagues “are crucial in ensuring healthy, normal development and implantation” and could help doctors refine fertility treatments. Braude is not connected to Niakan’s research.
There are a few methods of gene editing, but the technique Niakan’s team plans to use is known as CRISPR-Cas9, a relatively fast, cheap and simple approach that many researchers are keen to try. It is also the one best suited for editing the genome of still-developing embryos.
But such so-called “germline modification” means that DNA changes, if the embryo were allowed to live and become an adult, would be passed on to its offspring, effectively tinkering with the process of evolution.
CRISPRs — “clustered regularly interspersed short palindromic repeats” — are an immune defense system found in bacteria to protect against viruses.
Relative to other methods, they can be easily engineered to home in on the exact spot where a break in the genome should be made.
Once a sequence of DNA is broken, scientists can trigger one of two kinds of repair mechanisms. One requires using a DNA fragment as a template — including the new sequence to be inserted — for the repair.
The other does not need a template, and simply patches the rupture in the genome.
Some critics warn that tweaking the genetic code in this way could be a slippery slope that eventually leads to designer babies, where parents not only aim to avoid inherited diseases but also seek taller, stronger, smarter or better-looking children.
Many religious groups, including the Catholic Church, object to people “playing God” and manipulating embryos. Some scientists have voiced concern that tampering with genes might have unintended consequences not apparent until after the babies are born — or generations later.
Some fear such tinkering will only widen the gap between rich and poor by enabling the wealthy to create superbabies.
“This is the first step on a path that scientists have carefully mapped out towards the legalization” of genetically modified babies, David King of the advocacy group Human Genetics Alert said last month when British regulators took up the issue.
Around the world, laws and guidelines vary widely over what kind of research is allowed on embryos, since such experiments could change the genes of future generations.
Countries such as Japan, China, India and Ireland have unenforceable guidelines that restrict editing of the human genome. Germany and other countries in Europe limit research on human embryos by law.
Chinese researchers announced last year they manipulated the genomes of non-viable human embryos, looking for a way to correct a rare and fatal blood disorder.
At an international meeting in Washington last year, scientists agreed that attempts to alter early embryos as part of laboratory research should be allowed but that the technique was nowhere near ready for use in pregnant women.
Last year, British lawmakers voted to allow scientists to create babies from the DNA of three people to prevent children from inheriting potentially fatal diseases from their mothers. In doing so, Britain became the first country to allow genetically modified embryos to be transferred into women.