Researchers at Newcastle University have successfully created embryos that contain the DNA of three people.
It is hoped that within the next three years, this technique will be used to help women who have mutations in the DNA in the mitochondria, which can lead to disorders that include fatal liver failure, stroke-like episodes, blindness, muscular dystrophy, diabetes and deafness.
The mitochondria contain 37 genes, all of which code for proteins that are essential for normal mitochondrial processes. Compare this to the total number of genes in the human genome (20,000-25,000), and you can see that they only make up a very small percentage. But, because the egg from the mother contains this damaged mitochondrial DNA, it is passed onto her children, and at the moment there is no way of stopping these disorders being inherited.
The technique relies on two procedures that have already been developed – IVF and enucleation (which is used in cloning).
The research team started by using IVF to create a fertilised egg from a mother with malfunctioning mitochondria, then extracted the nucleus. Next, they took another fertilised egg from a second, donor mother, and removed the nucleus. These two elements were then combined – the healthy DNA from the natural mother and father was placed in the donor mother’s egg – to create a new fertilised egg with DNA from three people. Only the nuclear DNA was transferred, the mitochondria was left in the discarded egg. This means that the embryo had nuclear DNA from one woman, and mitochondrial DNA from another.
Discussing this new technique is a great way of making lessons on genetic disorders, fertility treatments and genetic engineering topical. In order to use it in a lesson, the technique needs to be explained carefully and upd8 produced a resource back in February 2008 (after the team first showed that the technique would work) that contains easy to understand explanation of how it works.
You could then go on to discuss the many ethical dilemmas that surround this procedure. Students can study each of the arguments below, and then apply their knowledge of the technique and inheritance to say whether they are a good argument against this technique being used in the future, or not.
This is cloning humans.
There are other methods to stop the passing on of these damaged mitochondrial genes.
The resulting embryo will have the DNA of 3 parents which leads to the mother of the donated embryo having parental rights.
This is a step towards ‘designer babies’ – letting parents choose the traits of their children.
Scientists are creating a new life by destroying another.