Powerhouse. Mitochondria in lung cell.
Louisa Howard / Wikimedia Commons
criticism of fertilization potential in vitro (IVF) strategies to prevent babies from developing a common class of genetic diseases is sparking Controversy. In today's issue of Science three evolutionary biologists argue that ethical and scientific debate on an approach to experimental IVF called mitochondrial replacement minimized potential risks of the technique. While the trio further support the development of the therapy, they say that other animal studies may be needed before clinical trials should proceed. But supporters of the art and IVF key regulator in the UK say that the concerns have been addressed and are minor compared to the symptoms of technical prevent.
Mitochondria are organelles that provide cells with energy. The replacement of these power plants in egg cells has been proposed for women who carry mutations in their mitochondrial DNA (mtDNA), but still want to make a baby. (Mitochondria carry their own DNA, which is inherited almost exclusively by the mother, although spermatozoa mitochondria, they degrade after the fertilization of an egg.) Mutations in mitochondrial DNA can cause mitochondrial diseases, with an range of symptoms affecting the eyes, heart, brain and other organs. Some cases are mild; others are fatal.
The researchers worked to develop ways that women who carry mutations of mtDNA may have biological children without passing on the defect. Several methods are being developed, but they all involve replacing defective mitochondria from the egg of a patient with those of a healthy donor. The techniques raise ethical concerns because they involve changing the heritable DNA of an embryo "babies Three Mothers" is often part of the title that accompanies stories about the concept. In the UK, several ethical review committees scientific and technical gave cautious support, however, and the government has said it wants to allow the technique. It is planned to publish the proposed regulations in the coming months, and the UK Parliament could vote on a final version of the next year.
a number of animal studies have shown that the technique can produce live offspring, and a study last year showed that it can produce normal-looking human embryos, at least the blastocyst stage, about five days after fertilization. Some proponents of the technique compared to the evolution of the battery in a camera.
Klaus Reinhardt , an evolutionary ecologist at the University of Tübingen in Germany, and his co-authors say that this analogy is too simple. They say animal studies suggest that interactions between mtDNA and nuclear DNA are numerous, and minor changes in either can affect mitochondrial function. MtDNA donor presentation could lead to subtle problems in offspring that has not yet been studied in the only primate model for mitochondrial replacement: macaques. In mice and fruit flies, Reinhardt said, the problems of exchange mitochondria appear disproportionately in men and often affect fertility. macaques published studies on mitochondrial replacement follow the new offspring for 3 years, but men do not reach adulthood until 4 years, Reinhardt said.
The Human Fertilisation and Embryology Authority UK (HFEA), which would be in charge of regulating the technical if allowed in the UK, said his group of experts took these concerns into account. The panel "carefully examined the interaction between mitochondrial and nuclear DNA and concluded that the evidence did not demonstrate cause for concern," the agency said in a statement today. The agency talks with committee members to consider the question whether the monkeys in the study were followed long enough, a spokesman said.
geneticist Robin Lovell-development Badge of the MRC National Institute for Medical Research in London, who co-chaired the Scientific Review Committee HFEA, said he does not know of evidence that interactions between mitochondrial and nuclear DNA could cause serious health problems in humans. If treatment can lead to side effects, "it is important that the family knows that risk," he wrote to Science Insider in an email. However, he adds: "I think they would still choose [mitochondrial replacement] rather than having a sick child"
Reinhardt said he agrees. "We are sure HFEA. decide [whether to allow the therapy] based on a case by case basis and will be guaranteed. But couples who have mild mitochondrial disease may choose to wait two years until the monkeys are a little more mature. "
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