Plans to allow the creation of so-called three-parent in vitro fertilisation (IVF) babies as early as next year are premature because of unresolved safety concerns about the future health of the children, a senior science adviser has warned.
The UK is poised to become the first country in the world to allow the creation of IVF embryos by merging the genetic material of two egg cells in order to prevent the transmission of mitochondrial disorders.
But the United States has decided it is still too early to permit the procedure, said Professor Evan Snyder, who chairs the scientific panel advising the US Food and Drug Administration (FDA) on mitochondrial transfer.
He said there are still too many safety issues to allow the first clinical trials of the technique in America and by implication in Britain, where the Governments own scientific advice is that the technique is not unsafe.
Parliament is expected to vote soon on whether to change the law and allow the mitochondrial transfer procedure in the UK, which could pave the way for researchers at Newcastle University to create the first three-parent IVF embryos by merging the genetic material of two eggs and a sperm as early as next year.
However, Professor Snyder said that it could take several more years of research to finalise the checks needed to ensure that the transfer of mitochondrial genes from a donor egg into a recipient egg will conform to the FDAs rules on the safety of clinical trials.
"The FDA panel was not in any way antagonistic towards this intervention. The diseases are terrible, the treatments are non-existent and the technology so far is a tour de force," Professor Snyder said. However, everybody concluded that there is still more work to be done.
"There needs to be a little more in-vitro work, there needs to be some more animal work, there needs to be longer-term follow-up on the offspring born from monkeys and probably other animals that have reproductive systems similar to humans," he said.
"We estimated how much time it would take to fill in these pre-clinical gaps and it looked like it could be anywhere from two to five years. Two years if things go well, five years if they go slower," Professor Snyder said.
About one in every 6,500 babies born each year is affected by inherited defects in the genes of the mitochondria, microscopic bodies in the cell cytoplasm that generate the energy needed to power each cell of the body.