WASHINGTON • CRISPR is a revolutionary gene-editing technique that allows scientists to insert, remove and correct DNA within a cell with pinpoint precision.
But gene editing is controversial because it involves altering the human genetic code. It also evokes a future where humans can order "designer" babies with specific features - blonde hair, athleticism, perhaps even intelligence. That, though, is some way off as scientists say we do not yet know how to genetically enhance such traits.
Yet, there is also the prospect of avoiding heritable, genetic diseases that can handicap or kill, meaning a chance to improve a human life.
For Professor Peter Braude, a reproductive health expert from King's College London, the study showed that "germ line genome editing has moved from future fantasy to the world of possibility". The debate about using it in practice "needs to run to catch up".
Professor Darren Griffin of the University of Kent, in Britain, said: "Perhaps the biggest question, and probably the one that will be debated the most, is whether we should be physically altering the genes of an IVF (lab- created) embryo at all.
"Equally, the debate on how morally acceptable it is not to act when we have the technology to prevent these life-threatening diseases must also come into play."
Currently, the only way to avoid heritable disease in assisted reproduction is to fertilise eggs in the lab, analyse the DNA of the resulting embryos, and eliminate those containing errors.
Much more research is needed before the method can be tested in clinical trials, now impermissible under US federal law. But if the technique is found to work safely with this and other mutations, it might help couples who could not otherwise have healthy children. Potentially, it could apply to any of more than 10,000 conditions caused by specific inherited mutations.
Researchers and experts said those might include breast and ovarian cancer, as well as diseases like Huntington's, Tay-Sachs, beta thalassemia, and even sickle cell anaemia, cystic fibrosis or some cases of early-onset Alzheimer's.
"You could certainly help families who have been blighted by a horrible genetic disease," said Dr Robin Lovell-Badge, a professor of genetics and embryology at the Francis Crick Institute in London, who was not involved in the study.
Concerns, though, remain.
A group of 11 organisations, including the American Society of Human Genetics and Britain's Wellcome Trust, on Wednesday issued a statement recommending against genome editing that culminates in human implantation and pregnancy, while supporting publicly funded research into its potential clinical applications.
AGENCE FRANCE-PRESSE, NYTIMES, REUTERS