Why does this procedure exist?
Mitochondria provide energy to nearly every cell in the body. Mitochondria is transferred from mother to the baby, but if there is a problem with the mitochondria inherited to the baby, then this can result in severe mitochondrial diseases. One in every 6,500 babies born have severe mitochondrial disease which can include muscle weakness, blindness, deafness, fatal heart failure, liver failure, learning disability and diabetes and can lead to death in early infancy.
In March 2015, MP’s in the UK voted to allow mitochondrial donation. This resulted in the United Kingdom being the first country to legalize the procedure. Experts from the Human Fertilisation and Embryology Authority (HFEA) stated that they would require more evidence that the procedure was safe before the end of the year, before they could consider issuing a license for doctors to perform the procedure.
Professor Turnbull from Newcastle University.
The process of Mitochondrial Donation
A team of scientists led by Dr Mary Herbert and Professor Doug Turnbull from Newcastle Univeristy have been the pioneers behind the technique. There are several, different processes that can be used for mitochondrial transfer. Scientists at Newcastle University published results on one form of mitochondrial donation called Pronuclear Transfer (PNT). This is when the mothers egg is fertilised with the fathers sperm using standard IVF procedures. Before the egg has a chance to divide into two, the parents’ chromosomes are removed and placed into a fertlised egg from a healthy donor, which has had it’s own own chromosomes removed.
The scientists concluded that healthy embryos created from mitochondrial transfer were likely to produce normal pregnancies. While this was positive, follow-up studies urged some caution. When cells were taken from PNT embryos in the lab, some showed rising levels of mutated mitochondrial DNA. Although small amounts are carried over, the faulty DNA came back. The scientists suggested they could screen PNT embryos for high levels of mutated mitochondria before deciding which to implant. Professor Turnball states “This procedure could potentially help 150 women who carry Mitochondrial Diseases in the UK each year. But many may choose alternatives to avoid passing the mutated DNA such as adoption or IVF with donor eggs.”
The Negative Outcry
Although the donor egg is said to only contibute 0.1% of the genetic make up of the child, when examining the genetic material of these children there are still three identifiable genetic parents. This is due to the fact that the donor egg usually comes from a non-maternal relative. For the child to have only two identifiable genetic parents, the donor egg must have to come from a paternal relative because mitochondrial DNA (mtDNA) is inherited maternally, maternal relatives will, have identical mitochondrial DNA, barring random mutations. Scientists have yet to explore the prospect of mitochondrial donation from paternal relatives. This means that currently any child born from this procedure would have three parents. However, the new proposed laws state that the identity of ‘the second mother’ would remain anonymous. This has raised some backlash because egg and sperm donators by law cannot remain anonymous as the child has a legal right to know where they came from. But, the mitochondrial donor has contributed DNA to the creation of the child, they are another parent so why are they not treated the same as egg and sperm donors.
The Council of Europe’s Convention on Human Rights and Biomedicine and the World Health Organisation stated that they are opposed to anything that alters genes across generations. But the result from parliaments vote showed that the benefits that mitochondrial donation can give to carriers of mitochondrial disease outweighs the ethical arguments against the procedure.
The Telegraph- Tim Stanley- www.telegraph.co.uk/news/health/11380784/Three-parent-babies-unethical-scary-and-wrong.html
BBC News- James Gallagher- www.bbc.co.uk/news/health-26367220
The Guardian- Ian Sample- https://www.theguardian.com/science/2016/jun/08/doctors-edge-closer-to-creating-babies-with-dna-from-three-people
BBC News- Fergus Walsh- www.bbc.co.uk/news/health-36481452
www.geneticsandsociety.org- CGS 3 person IVF