Brett Smith for redOrbit.com – Your Universe Online
A controversial yet lifesaving treatment that essentially engineers three-parent children using in vitro fertilization (IVF) and third-party mitochondrial DNA will move ahead with clinical trials in the UK, according to British officials.
The procedure involves taking dysfunctional mitochondrial DNA from a prospective mother and swapping it out for healthy mitochondrial DNA from a female donor. The technique, called mitochondrial transfer, is designed to prevent the passing on of debilitating genetic disorders from mother to child via mitochondrial DNA.
The UK government announced it would begin to allow doctors to apply for permission to perform the procedure, pending approval of regulations from parliament.
Mitochondria are described as the “power plant” of the cell and their dysfunction can result in disorders that affect the entire body – including the heart and brain. About 1 in 6,500 people is born with a mitochondria-related condition. The mitochondria are the only parts of human cells outside of the nucleus where DNA is found. Unlike nuclear DNA which is inherited more or less equally from the mother and father, mitochondrial DNA is inherited exclusively from the mother.
“It’s only right that we look to introduce this life-saving treatment as soon as we can,” said Dame Sally Davies, the chief medical officer in England.
A report from the Human Fertilization and Embryology Authority (HEFA) published in March said the UK public generally approves of the procedure, although some groups have contested the procedure because it includes the destruction of embryos.
The method could also have unknown generational consequences as it results in the passing on of modified genetic material. Mitochondrial transfer has been shown to work in animals but has never been tried on humans. Davies noted any babies born from the procedure need to be monitored closely.
“This is not a decision to take lightly,” she said, adding that mitochondrial diseases have a “devastating impact” on individuals and those around them.
“People who have it live with debilitating illness, and women who are affected face passing it on to their children,” she said.
Doctors have developed two different kinds of mitochondrial transfer. Both involve genetic material from the parents being injected into a donor egg containing healthy mitochondria that has had its nucleus removed. The resulting embryo carries nuclear DNA from the parents, but donor mitochondria – amounting to only about 37 of the genome’s 23,000 genes.
Current measures to battle mitochondria-related disease for high-risk mothers include in-vitro fertilization with donor eggs and adoption.
Davies said women who donate mitochondria would remain anonymous and untraceable.
“(The announcement) is excellent news for families with mitochondrial disease,” said Doug Turnbull, who led the Newcastle University team that developed the procedure. “This will give women who carry the diseased genes more reproductive choice and the opportunity to have children free of mitochondrial disease.”
Helen Watt of the Christian Anscombe Bioethics Center spoke out against the announcement, saying that the embryo is not a source of “spare parts.”
“Parenthood is about unconditional welcome of children,” she told The Guardian. “It is not about manufacture and control.
“Couples who do not want to take the risk of passing on mitochondrial disease might want to consider ethical alternatives like adoption, which are far preferable to pursuing dangerous techniques of genetic engineering which exploit both embryos and egg donors.”
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