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WASHINGTON – Scientists working on the borders of medicine fear that the turmoil caused by the reported births of genetically modified babies in China is jeopardizing promising research on how to change heredity to combat various disorders.
Researchers are quickly learning how to modify their DNA to fight diseases such as Huntington, Tay-Sachs and hereditary heart disease. They perform legally authorized experiments on laboratory animals and petri dishes without taking the ultimate step of creating babies. Now, they are also worried about a negative reaction against their work.
"The alarmists who claimed that scientists were not behaving responsibly in the development of the next generation of genetic publishing now have ammunition," said Kyle Orwig, a reproductive specialist in the US. University of Pittsburgh, who dismayed the hope of altering sperm production to treat infertility.
He said that the public clearly asked what kind of research he was doing: "Families contact me all the time", men who can not produce semen and who are not helped by today's reproductive care. 'hui.
A Chinese scientist sent a shockwave into the scientific community this week when he claimed to have tampered with the embryos' DNA in the hope of making them resistant to the AIDS virus. He reported the birth of twins and explained that another pregnancy could stem from his work.
For years, according to international guidelines, the editing of genes that can alter human inheritance – through eggs, sperm or modified embryos – should not be tested during pregnancy, until that scientists know if this practice is safe. One fear is that such experiments could inadvertently damage genes that could then be pbaded on to future generations.
China has ordered the arrest of apparently underground research by researcher He Jiankui and his team.
"That's what we're afraid of: it's not legitimate scientists. These are crazy people who would like to try it without even worrying about the consequences, "said Shoukhrat Mitalipov of the Oregon Health & Science University. to repair gene defects in human embryos.
If the outcry leads to the addition of restrictions to the current patchwork of rules about what can be studied and how, the field "will likely be rejected for decades," he added.
The challenge, said Orwig of Pittsburgh, is to "convince the community that it's a rotten apple but that it does not reflect what most people do."
There are several types of gene editing. Experiments to repair damaged genes in children and adults with diseases such as sickle cell disease are quite simple because this drug approach would only affect the patient and not his offspring.
The editing of genes from the "germ line", or the change of genes so that they are pbaded from generation to generation, is much more controversial. The big ethical question is whether such a craft should be limited to genes that can cause disorders that would otherwise not be treatable, or if medicine should be free to create "designer babies" with specific traits, such as 39, a high IQ.
"I think the public is probably open to fairly clearly therapeutic uses of this sort of thing, to prevent transmission of the disease. But there is significant discomfort, if not total opposition, to the use of the improvements, "said Josephine Johnston, an expert in biomedical ethics and policy at the Hastings Center, a bioethics research institute based in Garrison, WA. New York.
In a survey conducted last summer, the Pew Research Center found that most Americans – about 7 out of 10 – said it would be appropriate to modify the DNA of an unborn baby to treat a serious illness with which child would be born. But support declined sharply when people were told it would involve embryo studies.
And only 19% thought that modifying genes like improving intelligence would be appropriate, discovered Pew.
How to prove that gene editing is safe enough to be able to legitimately try in human pregnancies is an enigma, said University of Pennsylvania bioethicist Jonathan Moreno. "No regulator follows this child during his life, let alone his offspring," he noted.
Another question for ethicists: Even if it were considered safe, is the edition of embryo genes really necessary given current options? Already, families who can afford expensive in vitro fertilization can pay extra for the embryos to be tested genetically – and implant only those that do not have well-known dangerous mutations.
But such preimplantation diagnosis is not a solution for everyone, Johnston warned. IVF does not always produce enough embryos to allow couples to choose. And as tests reveal more and more disorders, people will have to understand that "there will be no perfect embryo," she said.
In Pittsburgh, Orwig considers that spermatozoa may offer a more practical first step towards germ line modification. Some male infertility is caused by genetic defects that prevent testicular stem cells from producing sperm properly. His team is studying sterile men to find the genes responsible.
His projects include: editing stem cell genes and implanting repaired cells in sterile mice to see if they produce sperm that lead to healthy baby mice.
The technique could be adjusted so that the genetic change is not necessarily pbaded on to the next generation, he said.
Young women who are already taking certain cancer treatments can already store ovarian tissue in the hope of a future pregnancy. Orwig said that it would be possible one day to delete, for example, a mutation of this tissue that could otherwise transmit the BRCA gene mutation of a family.
In the meantime, careful animal work with sperm could "lay the foundation for how it would be done in humans," he said. "When social conceptions change and policies change, we will be ready."
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AP Scientific Editor Malcolm Ritter in New York contributed to this report.
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This Associated Press series was produced in partnership with the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.
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