Last week MPs voted in favour of making the UK the first country in the world to permit IVF embryos to be created using DNA from three different people to help prevent mitochondrial diseases . A majority in the the House of Commons voted to approve an amendment to the 2008 Human Fertilisation and Embryology Act which will allow a mother’s mitochondrial DNA to be replaced by third party donor mitochondrial DNA . This in spite of some critics warning it was a step towards creating “three-parent” designer babies. Here I discuss the technique and look at the ethical issues that are raised.
Mitochondria-the “powerhouse” of the cell
Mitochondria are “organelles” found in cells that generate chemical energy, similar to the type of energy you get from a battery. The energy produced powers our metabolic processes. Mitochondria were actually once organisms in their own right, a type of bacteria. A billion years ago when the environment became difficult for survival these bacteria formed a symbiotic relationship with another organism. Over time the bacteria have evolved to become the mitochondria we see today, and a small part of the bacterial genome was left to form the present mitochondrial genome. Mitochondrial DNA contains vital information to make the proteins for generating cellular energy, 37 genes in total compared to the thousands of genes found within our chromosomes. All 37 genes are vital for cellular processes, and genetic mutation can result in a child inheriting a rare genetic disease. Symptoms can include muscle weakness, intestinal disorders and heart disease. None of the genes within the mitochondrial genome control our appearance.
Mitochondria are inherited maternally as mitochondria in sperm are broken down after fertilization. Research led by Professor Doug Turnbull has developed new IVF techniques which might have the potential to prevent women affected by mitochondrial disease passing the condition on to their future children. The technique involves removing the nucleus of a donor egg, leaving the rest of the egg contents including the “healthy” mitochondria, and the donor nucleus is replaced with the nucleus from the mother’s egg. This can be carried out either before or after the egg is fertilised with sperm. The result is an embryo with genetic material from its mother, father and the mitochondrial donor. But to put things in perspective, 99.8% of genetic material comes from the mother and father and 0.2% comes from the mitochondrial donor.
There are obvious ethical implications from creating an embryo with genetic material from three individuals. The technique introduces germline genetic changes in that the new mitochondrial DNA can be passed to the child's offspring. It is feared that approval of the technique could set a precedent for genetic alteration and be a move towards so-called designer babies. I agree that genetic manipulation should not be undertaken lightly, but with this technique only a fraction of the total genetic material contained in a cell is being replaced, and any resulting offspring will still have their parental traits. Mitochondrial disease causes severe illness and distress to affected families and if the potential to prevent such disease exists then an effective treatment should not be denied because approval might set a precedent.
Another consideration is should the details of the donor remain anonymous or does the child have the right to know who the donor is? Again an important point is that the genetic material being replaced does not affect appearance which would surely lessen the need to know who your “third” parent was.
I personally consider any social and ethical implications extending from the proposed techniques to change germ line mitochondrial genes are far outweighed by the benefits resulting from the birth of a healthy child. This is great news for progressive medicine, and Britain again is showing the rest of the world the way forward.