Thursday, June 5th, 2014
British researchers are close to developing a new medical technique in which genetic material from two women and one man are used to create an embryo that would not face the risk of mitochondrial diseases. The technique, if successful, would enable women who are carriers for mitochondrial genetic mutations to bear children. More from NPR:
“I think that [two years] is not a bad estimation,” Robin Lovell-Badge of the Medical Research Council tells . “The other sorts of experiments that we thought were necessary, again it will take about two years to complete all of those.”
The procedure targets problems in mitochondria, the energy-producing organelles that have their own DNA. Their genome is both prone to mutation and inherited maternally — characteristics that have led researchers to think up ways to help women who carry mutated genes to have healthy children.
The British panel has been reviewing two treatment methods that involve using either a donor embryo or a donor egg from a woman with normal mitochondria. The parents would contribute nuclear DNA, but the mitochondrial DNA would come from a donor.
Before that process occurs in Britain, it would have to be made legal. And as you might imagine, the review panel is also considering ethical and safety consequences.
“The direction of travel still suggests that it is all safe, but we don’t know what’s round the corner so we’re being a little cautious,” says Lovell-Badge, who is on a review board of Britain’s Human Fertilization and Embryology Authority.
The HFEA group saying evidence “does not suggest that these techniques are unsafe,” but that more experiments need to be conducted before clinical treatments begin. (You can ).
The process under review is often called oocyte modification, or more generally, three-parent IVF. In the U.S., convened meetings about a similar procedure in February, seeking expert and public comment.
Image: DNA map, via Shutterstock
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Thursday, April 17th, 2014
The protein mechanism that allows a sperm and egg to connect to each other and fertilize to become an embryo has been identified by British scientists. More from Reuters:
Fertilization takes place when an egg cell and a sperm cell recognize one another and fuse to form an embryo. But how they recognize each other in order to hook up had remained a mystery.
Researchers said on Wednesday they have identified a protein on the egg cell’s surface that interacts with another protein on the surface of a sperm cell, allowing the two cells to join.
This protein, dubbed Juno in honor of the ancient Roman goddess of fertility and marriage, and its counterpart in sperm, named Izumo after a Japanese marriage shrine, are essential for reproduction in mammals including people, they said.
This new understanding of the role of these two proteins could help improve the treatment of infertility and guide the development of new contraceptives, the researchers said.
“By identifying this interaction between Juno and Izumo, we now know the identity of the receptor proteins found on the surface of our father’s sperm and our mother’s egg that must interact at the moment at which we were conceived,” said Gavin Wright of the Welcome Trust Sanger Institute in Britain, one of the researchers in the study published in the journal Nature.
The researchers are now screening infertile women to try to determine whether problems with the Juno receptor are to blame.
“It is remarkable that about 20 percent of infertility cases have an unexplained cause,” said Enrica Bianchi of the Sanger Institute, another of the researchers.
“We are now asking whether Juno is involved in these cases of unexplained infertility,” Bianchi added.
Wright said that if defects in the Juno receptor are in fact implicated in human infertility, a simple, non-invasive genetic screening test could be developed to identify affected women.
“This then would allow us to guide the fertility treatment,” Wright said, letting affected women proceed directly to a procedure called intracytoplasmic sperm injection involving direct injection of sperm into an egg obtained from in vitro fertilization.
Image: Sperm and egg, via Shutterstock
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Monday, July 1st, 2013
Britain plans to become the world’s first country to implant genetically modified embryos. The methods are still in the research phase in both the US and Britain, but the techniques would help families avoid passing down incurable mitochondrial diseases through the maternal line—such as fatal heart problems, brain disorders, muscular dystrophy, and blindness—which affects one in 6,500 children according to NBC News.
The process works by replacing these faulty portions of the DNA with healthy segments from a donor woman, hence the name “three-parent” in vitro fertilization (IVF). Several approaches are being studied. Britain’s Newcastle University is studying pronuclear transfer, which swaps DNA between two fertilized human eggs. Another technique being developed is called the maternal spindle transfer, which swaps out the faulty DNA before fertilization. So far, studies have shown that these procedures are likely to be both safe and effective.
However, this kind of genetic intervention raises serious ethical questions. Critics worry that these procedures could pave the way for “designer babies,” with genetically modified features like height and eye color. Yet, in a national public consultation, Britons broadly favored the idea, making it likely that the procedures should be allowed to proceed under strict federal regulations.
New guidelines must be created to cover these treatments and are expected to be published later this year. If approved by a vote in Parliament, this would make Britain the first country to offer the option of mitochondrial DNA transfer to it’s citizens. Chief medical officer, Sally Davies, hopes the first patients will be able to undergo treatment in the next two years.
Image: Ultrasound of embryo, via Shutterstock
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