An experimental technique of assisted reproduction that could allow some families to avoid having children with certain types of diseases hereditary should be allowed to go ahead in the United States, provided it takes place slowly and carefully. This is the conclusion of a report released today from a panel organized by the US National Academies of Sciences, Engineering and Medicine (NAS), which assesses the ethical issues surrounding the controversial replacement therapy technique called mitochondrial DNA. (Part of the panel also summarizes the deliberations in a Policy Forum in Science .)
More controversially, however, the committee recommended that only modified male embryos should be used to attempt pregnancy, limit the possible risks for future generations. (Men can not pass along the mitochondrial DNA that is modified in the procedure.)
Mitochondria are organelles that provide energy to cells. They carry their own DNA, which encodes 37 genes, which is passed from mother to child through the mitochondria in the cytoplasm of the egg. (Sperm have mitochondria, but they are thought to deteriorate soon after fertilization.) Mutations in mitochondrial genes cause a series of problems, life-threatening some sweet and others. They tend to affect the tissues and organs that need a lot of energy, including the brain, eyes and muscles. Often the disease is progressive, and there are few available treatments.
Scientists have developed ways of transferring the genetic material of an egg with faulty mitochondria into a healthy egg, either before or just after fertilization. These techniques, known as replacement therapy for mitochondrial DNA (MRT), could theoretically allow women who are carriers of mitochondrial disease to have genetically related children. (Current options include adopting or using an egg donor.)
The embryo resulting from MRT door of three DNA: the current torque of nuclear DNA processing and mitochondrial DNA from the donor egg healthy. The prospect of these "embryos from three parents" and that any offspring pass their mitochondrial genes to their own children, made the controversial technique. So the US Food and Drug Administration (FDA) requested the review as part of its deliberations on whether to allow researchers to the United States to use the technique.
the potential benefits of MRT outweigh the problems, the NAS committee said, provided that work is progressing slowly. This means that women who are considered very likely to pass severe forms of mitochondrial disease should be candidates for early clinical trials.
In addition, to avoid the possibility that babies born by unforeseen problems MRT pass along to their own children, the Committee also recommended that only male embryos be used to start a pregnancy.
"This is the first time that this will happen in humans. We do not know how it will work," says Jeffrey Kahn, a bioethicist at the Berman Bioethics Institute at Johns Hopkins University in Baltimore , Maryland, who chaired the panel. "We thought it prudent to make sure it will not affect the individual for future generations and not born."
This restriction would add an additional burden couples interested in MRT, said Sarah Norcross, director of the state education Trust in London, an advocacy group that focuses on issues of infertility and surrounding genetic diseases. male embryos could not be healthy embryos that result from the already complicated process, she said, and in some cases it could mean that women would have to undergo collecting additional eggs procedures.
Kahn notes the recommendation is temporary, however. After early research shows that the technique can be safe, in addition to animal data are available on possible effects in future generations, regulators could consider loosening the restriction.
think long term
The Committee strongly recommends that all studies be designed so that the results of several studies may be combined to learn as much as possible on technical security. They also recommend that all children born by MRT be followed by researchers in the long term, so that the physical or even psychological effects could be better understood. This requires parental permission at first, but later require permission from the children themselves once they are old enough. This is a challenge, says Kahn. "You can not give consent for those who have not yet been designed."
The group also encourages the FDA to carefully consider how they can prevent other uses of technology. Some researchers have proposed using MRT to treat infertility related to age, for example, but that is not morally justified, the committee said.
This is a potential problem, said Marcy Darnovsky, executive director of the Center for Genetics and Society and advocacy group in Berkeley, California, who opposed the approval of MRT. "It is important to realize that if the FDA were to approve these techniques, it would have few mechanisms to prevent what would essentially" off-label uses, "says Darnovsky in a statement. "An American promoter of these techniques has already made clear publicly he would like to expand their use largely to fertility clinics. Their use could easily spiral out of control. "
After years of scientific and ethical debate, the UK passed a law last year that would allow fertility clinics here to provide technical, but in each case if and closely supervised by the human fertilization and embryology countries (HFEA), which regulates assisted reproduction and embryo research. No clinical has not received approval to use the technical there.
the United States has no equivalent to HFEA, but the FDA said that all those who want to use the technique must apply to the agency for approval because that MRT is a form of gene therapy. in 2014, he began a process to evaluate the scientific and ethical issues surrounding the technology. the NAS report will help the FDA decision form of regulations and guidelines for such applications.
But do not expect such experiments to proceed rapidly in the United States. Federal legislation passed in December limits the ability of the agency to grant permission to all mitochondrial replacement therapy efforts for the year 2016. Due to the legislation, a spokesman for the FDA noted in a email, "the agency does not receive or INDs [Investigational New Drug applications] examination to the research about humans using genetic modification of embryos to prevent transmission of mitochondrial disease during the 2016 financial year and research the human subject using these technologies can be conducted in compliance with the Federal Food, Drug and Cosmetic Act and FDA implementing regulations. "
* Update, February 4, 5:55 p.m.: This article has been updated to include comments from the FDA and the link to science political forum. "
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