VOA慢速英语--First Human Embryo Gene-Fix Could Help Stop Disease

 

Scientists in Oregon successfully fixed a disease-carrying gene in human embryos. It was the first time this has been done.

This small effort could be a big step in preventing inherited, or gene-related diseases.

A research team at Oregon Health & Science University edited out a gene that causes a heart problem and kills young people. Their work was published in the journal Nature.

Dr. Paula Amato is one of the scientists who worked on the study. She explained how it happened.

The team used sperm from a man who carries the heart-damaging gene. They injected his sperm into eggs, and at the same time injected a gene-editing tool called CRISPR-Cas-9. The CRISPR acts like scissors - cutting out the defective DNA.

What happened next is surprising: The embryos then fixed the DNA themselves, replacing the damaged part, without more help from the scientists.

Amato says the gene defect correction rate was high, about 70% of the time. She says their success is proof that it can be done.

“It's very preliminary at this point but the potential is huge. But obviously much more research needs to be done before it moves to clinical trials.”

With 10,000 gene defects that cause disease, there would be no shortage of ones that could be fixed. But scientists are a long way from knowing how this would affect a baby.

“The biggest thing is safety. We don't know if this truly would be safe in, if we ever tried it to establish a pregnancy and produce a baby. But that’s [the] biggest ethical concern in my mind.”

The ethics of editing genes

Safety and ethics are also on top of Dr. George Daley’s mind. He is a stem cell scientist and the dean of Harvard Medical School. Daley was not involved in the study but he calls it “a remarkable story.”

Daley says, if safety concerns are taken care of, “the question we are left with is: should we do it?” And for whom?

“I tend to believe that for certain rare instances where we're trying to prevent a devastating genetic disease that this could be indeed if, in the long run, proven safe, could be a very useful and life-affirming application of medical technology.”

But Daley says this technology should not be used for enhancing, or improving human capabilities. That is what some call “designer babies”—parents creating features they want in babies.

Concerned that some doctors might abuse gene editing, Daley says there should be independent supervision by professional groups to observe this work. But based on just this one study, he says it is far too early to use it in any way for making babies.

For now, people wanting to avoid passing on a bad gene sometimes have embryos created in fertility clinics. Those embryos are checked, and only the ones without the bad gene are used to attempt pregnancy through so-called in vitro fertilization process (IVF).

Marcy Darnovsky says in vitro fertilization avoids inherited diseases. She is with the Center for Genetics and Society in California. She is speaking out against the new gene editing.

“This is not a technique that treats or cures anyone. It’s not really a medical technique at all. It’s about creating new human beings that have their traits determined and engineered.”

She says because of its high cost, it would only be available to wealthy people, creating “another kind of inequality” in the country.

Laurie Zoloth is the dean of University of Chicago Divinity School. She says many religions see human babies as a gift from God.

“From some religions there arises a concern that controlling evolution in this way gives human beings too much power” over what is God’s creation, she says.

Arthur Caplan supports the idea of the gene editing technique. An expert in bioethics, Caplan heads the Medical Ethics Division at New York University School of Medicine.

He says it would be good to do away with genetic diseases like cystic fibrosis, hemophilia and sickle cell anemia. These are examples of terrible genetic diseases for which there is no cure. And Caplan adds not all genetic diseases can be eliminated by using IVF.

“Finding ways to prevent them from being passed on to one’s children and grandchildren would be a wonderful achievement, one that I find it hard to argue has any objection in terms of eliminating disability and premature death and stopping something that's plagued all of mankind forever, inheriting genetic diseases.”

The effect of editing genes

It is not known how permanently changing the genes may affect the following generations. Changing genes may produce children that are sick, much like the sheep Dolly. She was cloned in 1996—made from a genetic copy of another sheep—but she grew sick and died early.

Caplan says history tells us to wait and see how the technique works in animals first.

“Let’s see how they turn out after a few years and then we'll start to get excited about using this technology to really prevent disease in people. Then we can really argue about whether it’s better to screen the embryos and throw them away or fix them.”

The U.S. is not alone in doing this scientific research. Caplan says other countries like China, Britain and Singapore are also editing, or planning to edit, genes.

Like Harvard’s Dr. Daley, Caplan is calling for a group of scientists, ethicists, lawyers and others to create rules and observe the work of scientists editing genes. The rule making should come from the private groups, he says, not the government.

I’m Anne Ball.

Words in This Story

edit – v. to make changes, correct mistakes, etc., in something

defect – n. a problem or fault that makes someone or something not perfect

preliminary – adj. coming before the main part of something

ethics – n. rules of behavior based on ideas about what is morally good and bad

devastating – adj. causing great damage or harm

affirm – v. to say that something is true in a confident way

enhance – v. to increase or improve (something)

evolution – n. the process by which changes in plants and animals happen over time

in vitro fertilization - n. fertilization of an egg in a laboratory dish or test tube

plague – v. to cause constant or repeated trouble, illness, etc.,