Just as scientists in the UK are about to begin clinical trials with three-parent embryos, a study in Nature asserts that it may not work for some patients.
The technique is intended to help women who are carriers of mitochondrial disease to give birth to healthy children. The nuclear DNA is removed from an egg cell, leaving the diseased mitochondria behind; then the DNA is inserted into another woman’s denucleated egg to make use of her mitochondria; and then the egg is fertilised. The resulting embryo will grow, hopefully, into a disease-free infant with three genetic parents.
One hitch is that, with current techniques, some of the rogue mitochondrial DNA is dragged into the new cell along with the nuclear DNA. It was thought that this would be too small to matter. However, a paper published this week in Nature by mitochondrial geneticist Shoukhrat Mitalipov, at Oregon Health & Science University in Portland, suggests that the DNA carrying the disease sometimes “out-competes” the healthy mitochondrial DNA and could cause the disease.
“It’s not perfect. There’s this chance of something going wrong,” Robin Lovell-Badge, a leading UK stem cell scientist, told Nature. Patients “must understand it’s impossible to ensure total safety until clinical trials have taken place”.
The scientists’ misgivings are unlikely derail clinical trials for the three-parent embryo technique. The UK’s fertility watchdog, the Human Fertilisation and Embryology Authority, recommended this week that mitochondrial donation techniques be approved for “cautious” use in “specific circumstances” even though it was well aware of this complication.
In fact, it is being argued that the dangers make the trials all the more urgent. The technique has already been tried in Mexico and Ukraine, where there is less regulation. If trials are conducted by reputable scientists, there will be certainty about how effective the technique is. The more we hold off, patients will seek treatments elsewhere,” Mitalipov told Nature. “The whole idea of conducting it in the UK and US is that we do it in a few clinics under strict oversight as a clinical trial, so we can evaluate these clinical outcomes."
California’s assisted suicide law came into effect on June 9. Betsy Davis, an artist with ALS, also known as Lou Gehrig’s disease, was one of the first to take advantage of the legislation. She drank a lethal cocktail on July 23, after a long party with close friends. I’m afraid that we missed the story at the time.
Reading her sister’s account of Betsy’s death, which is full of loving sorrow at her passing, I was struck by how quickly Californians started to ignore all the careful safeguards. It is clearly specified in the law that the person must “self-administer” the drug. But she was too weak to hold the cup and drink it quickly, so her friends held it for her. They may have broken the law.
People tend to think that a lethal barbiturate brings about death quickly. This wasn’t true in Betsy’s case – she lingered on for four hours. Given that the drug was a homemade cocktail of morphine, pentobarbital and chloral hydrate which smelled like paint, her friends were “lucky” that it worked. Some assisted suicide patients in Oregon have woken up to discover that their suicide has failed.
It wasn’t a good beginning for the law.
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