Scientists striving to create a three-parent baby have discovered that mutated DNA can in fact be passed down to the child during the innovative procedure.
University of Newcastle scientists had been experimenting with the process to see if replacing an egg’s disease-prone mitochondrial DNA with that of a healthy female donor could head off inherited conditions such as muscular dystrophy.
The process is considered to be controversial because it could lead to the child having the DNA of three parents – the extra one being from what is effectively a second mother.
Parliament has allowed the process to go ahead, but further tests have been called for by the Human Fertilisation and Embryology Authority (HFEA).
On Wednesday, scientists announced that despite some successes with the process, there was a risk of up to four percent of mutated, disease-causing DNA carrying over.
Tests on a number of embryos showed that in one case the DNA grew to illness-inducing levels over a period of time.
Newcastle University’s Professor Mary Herbert told the Telegraph: “We don’t know what it means for development, but it’s alerted us to the fact that we really need to work hard to get as close to zero carry-over as we can.”
“It sounds a note of caution for us,” she added.
Nevertheless, the scientists said there were positive signs that birth defects and issues that may cause miscarriage were not detected in the testing.
The HFEA is due to meet over the next few months and carry out assessments on the new evidence. If they are convinced the first three-parent baby could be born as soon as next year.
The cutting-edge study involved over 500 eggs from more than sixty donors and its results were published in the Nature scientific journal.