A baby, the first child born in a new technique that incorporates the DNA of three people, is now five months old. It is great news -. The birth of a healthy baby conceived by this new procedure is a major step forward and will lead to a new way to prevent inheritance of mitochondrial diseases
Mitochondria are the power plants of cells. Generate energy for all life processes. One of every 400 people has a maternally inherited mutation in mitochondrial DNA (mtDNA), the model for some vital mitochondrial components. MtDNA mutations can cause a variety of diseases, including deafness, blindness, diabetes and heart and liver failure. People with these disorders often have both normal and damaged mtDNA, with symptoms usually worse the higher the dose of mtDNA damage. Unfortunately, there is no cure.
In mitochondrial replacement therapy (MRT) embryos the couple at risk of having an affected child are generated in a test tube. In this case, the core containing the entire genetic material, apart from the mitochondria egg was removed from the mother and placed in an egg with healthy mitochondria, of which the core had been removed. then the egg was fertilized with the father’s sperm and the resulting embryo is placed in the uterus of the mother where he became the baby.
This means that the baby has three genetic parents: the father who provides the sperm, the mother who provides both the belly and the egg nucleus and an anonymous donor who provides healthy mitochondria. Of these, mitochondrial DNA is by far the smallest contribution. This type of three-parent baby is new, although other types have existed for many years.
MRT is being developed by groups in the United Kingdom and the United States to help families of patients with mitochondrial disease with a high risk of recurrence in future children.
unknown long-term effects
While experiments with monkeys and mice suggest that these babies would probably be healthy, this procedure had not been used in humans so far. Eggs are highly organized cells. Replacing the core does not prevent development in a baby, but causes damage to the cell that probably requires a radical reorganization. Therefore, the effects of such manipulations are still unknown and may cause problems later in life, such as an increased risk of diabetes.
According to a report in New Scientist, the child’s mother, a Jordanian woman, they had been trying for a family for 20 years. His two sons died of Leigh syndrome – older than eight months and six. The woman had a high risk of having affected children more.
In many countries, the mother would have other options before MRT offered. First, it would have been offered eggs from a healthy donor unrelated. These could be fertilized with sperm from her partner and placed within it, preventing the transmission of the complete mitochondrial disease. The woman with the disease mtDNA is then biological, but not the genetic mother. Being the son of a woman who is not his genetic father may be acceptable for some people, and maybe even one in 10 people in the UK are not their genetic parents correctly identified -. But it may have been unacceptable for this family
She also would have been offered preimplantation genetic diagnosis in which several embryos can be tested at an early stage and the best selected to be placed in the uterus of the mother. However, according to reports, this was not ethically acceptable to this family.
The birth of a healthy baby after this technique is a great step forward. In recent manipulations related to improve the “quality of oocytes mitochondrial” have been carried out – the “ooplasma donation”, which involves the donor mitochondria that are injected into a germ cell in the ovary (an egg). However, this method reportedly caused genetic defects and perhaps autism in a case.
Although it is not possible to give the last baby a decisive “out of danger”, which carries a low level of harmful mutation, so it is very unlikely that it will develop Leigh syndrome.
The known unknowns
However, there are two more details of the story that could affect what happens next. First, the procedure could be called “medical tourism” has been made in Mexico by a team based in New York City, so it was not covered by US regulations that do not allow the procedure. The Institute of Medicine Committee on considerations of ethical social policy and innovative for the Prevention of maternal transmission of diseases of mitochondrial DNA refused to give regulatory approval for clinical use of the procedure up technical research to answer security questions and critical efficacy has been done.
Another problem is that not told how high the level of damage in mtDNA was in the egg of the mother before the procedure was carried out – a detail that indicates the likelihood that the child was It is severely affected from the beginning. If the level and, therefore, the risk was high, this is a laudable technical achievement that has greatly reduced chance of suffering a serious illness of the child. If the level is low and compatible with a healthy lifestyle, then an unknown procedure could have been done unnecessarily – that illustrates how we need regulation to protect the rights of the unborn child. The reports do not clarify these vital details.
This story is the beginning of a new treatment with enormous potential for good. However, stringent regulation and controls of the unknowns of this new and controversial technology is needed.
Author: Joanna Poulton, Professor at the University of Oxford
Courtesy: The Conversation