British scientists investigating the causes of miscarriage have applied for permission to modify the genes of human embryos, their institute has confirmed.
The controversial technique is illegal as a treatment but allowed for research purposes under strict conditions.
Researchers at the Francis Crick Institute in London want to employ an advanced “gene editing” method of making precise changes to DNA to alter the activity of genes in early-stage embryos.
The scientists also plan to use “transfection” techniques that involve inserting genetic material into cells.
The embryos, consisting of just a small number of cells, would be donated by couples undergoing IVF treatment who do not need them.
Under the 2008 Human Fertilisation and Embryology Act, they can only be used for basic research, must be destroyed after two weeks, and cannot be implanted in the wombs of women.
If the application to the fertility regulator, the Human Fertilisation and Embryology Authority (HFEA), is successful, work could begin straightaway.
Dr Kathy Niakan, who heads the research team, said: “To provide further fundamental insights into early human development we are proposing to test the function of genes using gene editing and transfection approaches that are currently permitted under the HFE Act 2008.
“We also propose to use new methods which allow very specific alterations to be made to the genome. By applying more precise and efficient methods in our research, we hope to require fewer embryos and be more successful than the other methods currently used.
“Importantly, in line with HFEA regulations, any donated embryos would be used for research purposes only. These embryos would be donated by informed consent and surplus to IVF treatment.”
By homing in on genes at play within the first few days of fertilisation, the scientists hope to shed light on why some women lose their babies before they are due to give birth.
They will use a technique called “CRISPR/Cas9” - an immensely powerful method invented three years ago that allows DNA to be “cut and pasted” using molecular “scissors”.
It could lead to huge leaps forward in science and medicine but critics have warned that the pace of change is too fast.
They fear misuse of such technology could lead to potentially dangerous treatments and “designer babies”.
One major concern is that making changes to embryonic DNA could have unknown harmful effects throughout an individual’s body.
There is also the risk of passing genetic “mistakes” on to future generations.
An HFEA spokesman said: “We have recently received an application to use CRISPR-Cas9 in one of our licensed research projects, and it will be considered in due course.”
Josephine Quintavalle, from pro-life group Comment on Reproductive Ethics, said: “We’re opposed to any destructive research on human embryos.
“With genetic modification approaches, the only proof of principle is to go on to allow pregnancies to continue, and then what are you going to do?