Three on one

Australia legalized mitochondrial donation, opening the way to triple parenting

Marina Astvatsaturyan, "Search"

The Australian Senate has passed a law by a majority vote legalizing the clinical use of donor mitochondria, BioNews reports. To the general public, this document is known as Maeve's law – after a five-year-old girl, Maeve Hood, who was born with Ley syndrome, a severe mitochondrial disease diagnosed at her age of one and a half.

Mitochondria are intracellular structures, organelles, in which energy is produced for cells. They are transmitted to the offspring through the egg, that is, they are inherited from the maternal line. Mitochondria have their own DNA (mtDNA), and some mutations in it lead to severe diseases associated with impaired energy functions. Ley syndrome is one of these diseases. Initially, mtDNA mutations were considered extremely rare, but a study of 3,000 healthy newborns on the 10 most known pathogenic mutations conducted in 2008 revealed those in one person out of 200. Mitochondrial donation, which is the basis of mitochondrial replacement therapy, allows mothers carrying defective mitochondria to pass on to their offspring all their genetic material, except mitochondrial, because the bulk of our DNA is in the cell nucleus, while mitochondria float in the cell outside the nucleus.

Mitochondrial replacement therapy works as follows: its nucleus is removed from the donor egg, which is replaced by the nucleus from the mother's egg, and the healthy mitochondria of the donor cell remain intact and in the same cell where the main genetic material of the mother was placed. Such an egg with the donor's mitochondria, but the mother's nucleus, is artificially fertilized with the father's sperm. The resulting fertilized egg is then transferred to the uterus of the mother, who bears the fetus. This procedure is often called three-parent artificial insemination, because the child inherits DNA from three biological parents, although the genetic contribution of the egg donor is minimal.

The first country to approve mitochondrial donation at the legislative level was the United Kingdom, Australia was the second. But in the world, this procedure causes acute ethical discussions. So, in the USA, mitochondrial donation is prohibited due to the current ban on the creation of human embryos with inherited genetic changes. Critics believe that the genetic material of donor mitochondria is an inherited change because it differs from the material of the father and mother of the embryo. While some see the use of donor mitochondria as an extension of the possibilities of artificial insemination, others argue that this will open the door for genetic editing of embryos, up to "human improvement".

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