Three-Person IVF: Science Shows Ethical Questions Remain Unanswered

Diseases caused by genetic mutations in the mitochondria – the powerhouses of the cell – can be disabling, or even deadly. That is why mitochondrial replacement therapy (MRT), otherwise also known as three-person IVF (in vitro fertilisation), is being touted as a much-needed option for women carrying mitochondrial mutations.

Most genes in a cell are trapped in the nucleus, but a tiny fraction are present in the mitochondria too. When eggs are fertilised, the genes in the nucleus of the egg combine with the genes in the nucleus of the sperm to create a new cell. However, mitochondrial genes do not undergo this mixing and are passed on from mother to child.

The idea behind three-person IVF is to find a way of replacing the mitochondrial genes in an affected egg cell before they are passed on to the child. This is done by acquiring a donor’s egg cell and removing the nucleus from it to leave a cell with healthy mitochondria. Then the mother’s nucleus, which is unaffected, is removed and placed in the donor’s egg...