The British government supports an assisted-reproductive technique that allows the transmission of certain genetic diseases to be eliminated, using DNA from three different people
The press worldwide has published the decision of the British Secretary of State for Health to support assisted reproductive technology which uses the DNA of three people to prevent the transmission of mitochondrial genetic diseases from mothers to children. Mitochondrial diseases are included in the group of what are considered “rare diseases” and develop because the mitochondria of the persons suffering form the disease – which are similar to the engines of the cells in the body – are defective.
The debate is under way and with it, several questions related to this treatment. The Eugin blog and its scientific director, Rita Vassena and medical director, Amelia Rodríguez, aim to provide a response to some of these questions.
What does the treatment consist of?
The objective of this reproductive technique is to eliminate the genetic information from the mother which contains the part of the cells that transmits this type of disease. To do this, an egg is needed from a donor to which all the genetic material from the mother is passed, except for the content of the mitochondria. This way, a healthy egg is obtained which will contain the whole human genome of the mother, while the donor egg will only contain the mitochondria. That egg will be fertilised later with the male sperm through an in vitro fertilisation process. Consequently, the embryo resulting from this pioneering technique will have DNA from three different people.
But in genetic terms, whose child will it be?
Although the genetic information of three people is involved in creating the embryo, the intervention of the egg donor will be practically negligible in this case. Thus, while the parents will be responsible for about 20,000 inherited genes, the donor will contribute only 37 genes from her mitochondria.
Who can benefit from this assisted reproductive technology?
This technology is intended for women affected by mitochondrial diseases. Their mitochondria are defective and may cause diseases. The use of the mitochondrial technique prevents this genetic information from being passed on from mothers to children.
Is this the first time that this technique has been used?
Yes, in the case of human reproduction for eliminating mitochondrial diseases. However, in animal reproduction, this technique has been used for twenty-five years.
When will it be approved in the United Kingdom?
Although the Secretary of State for Health has already expressed support for the mitochondrial transfer technology, it is expected that the treatment will not be implemented until at least the end of 2014.
What does this technology mean for families affected by mitochondrial diseases?
It entails a great breakthrough for women affected by mitochondrial disease, as it will enable them to have children with their own genetic information but without the risk of passing on their disease to them.
How many people are affected by these diseases?
Mitochondrial diseases belong to the “rare diseases” group and their effect on the population is extremely scant and variable according to sources consulted. It is calculated that one out of every 5,000-10,000 births will be affected by this type of disease.
What are the symptoms?
This type of disease is usually progressive and affects several organs at once. It is mostly diagnosed in childhood with 50% of cases showing symptoms during the first year of life. It has a high mortality rate and may affect any organ. However, it mainly affects the muscles, the heart, the kidneys, the pancreas, the liver and the central nervous system, as well as the retina.