A scientist says he altered the genes of two baby girls. How big a line did he just cross?

If genetics researcher He Jiankui has provided an honest account of his new experiment, there are twin baby girls alive in China right now, and He altered and edited their genes. 

This news — if proven to be true — is an unprecedented event for our species; an event that is all at once daring, irresponsible, and revolutionary. And at some point in the future, this event could be the means of staving off afflictions like cancer and neurodegenerative diseases. 

He revealed the successful birth of the twins to the Associated Press on Monday and again at a conference on Wednesday. He used a powerful but still new gene-editing tool, known as CRISPR, to rewrite a portion of the girls' DNA. Specifically, He altered a gene to make the cells more resistant to the HIV virus. On the surface, this is a laudable goal. But scientists emphasize that altering human DNA is still too new a technology, and with it may come unforeseen, permanent risks to the human body.

"You have someone who’s taken a gigantic leap without any safety ropes or discussion," Arthur Caplan, a bioethics professor at the New York University School of Medicine, said in an interview.  

"You don’t set off to change the genes of our descendants without proving it's safe enough."

Scientists globally are already experimenting with manipulating genes, largely with mice. It's hugely progressive, innovative research. 

But, to the international community's knowledge, no one working with the technology had created a CRISPR-altered living baby until now, assuming He is being honest about his research. 

"It’s crossed a line that I think all responsible scientists and ethicists have established with respect to gene editing and CRISPR," Daniel Sulmasy, a medical ethicist at Georgetown University, said in an interview. "This is not to be done on human embryos that are going to be brought to term."

The crux of the problem is that manipulating genes — even if the goal is moralistic — has unintended consequences. 

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He claims to have altered the CCR5 gene, which allows the HIV virus to access a cell. Disabling the CCR5 gene, then, certainly might make someone quite resistant to contracting HIV. But what else might it do?

"We have no idea what changing that gene will do to the brain, the liver, and the immune system — and I think that is irresponsible," said Sulmasy.

CRISPR is revolutionary

Genetic material, or DNA, can be thought of as being comprised of many different configurations of four letters (A, C, G, and T) that represent four different molecules, called nucleotides. 

CRISPR works by designing another genetic fragment (a protein called RNA) that matches with the DNA's letters, and then can change, edit, copy, and paste them. 

"CRISPR has been revolutionary — it's been powerful," Richard Gronostajski, a biochemist and director of the Genetics, Genomics and Bioinformatics Graduate Program at the University at Buffalo, said in an interview. 

But our genome is vast, Gronostajski, emphasized. And that CRISPR protein may invariably match or closely match with another gene, and consequently change that gene, too. 

"They are not the changes you want to make, but they occur anyway," said Gronostajski. "Something very similar will be present in another [DNA] location." 

He sees this happen in mice. While deleting one gene won't carry other, unintended consequences in one strain of mice, it can have different, harmful effects in other mice populations, Gronostajski noted.

Now, two baby girls in China may be hit with these consequences. It's still unknown how or what might happen. After all, it's an experiment. 

"Is it fair to use humans beings as guinea pigs? The scientific community thinks it's just not the right thing to do," said Gronostajski.

"This is far too premature," added Sulmasy.

Our gene edited future?

The scientific community, however, has high hopes for gene-editing in the future — if it's ever proven to be safe.

For example, there's a notorious gene, the p53 gene, that has mutated in around 40 percent of cancers, said Gronostajski. The p53 gene normally suppresses tumor cells. Manipulating this gene to halt cancer works in mice. Perhaps one day it could do the same for humans. 

"Wouldn't that be a laudatory goal to have?" asked Gronostajski.

"In the long term, one would want to be able to correct genetic defects prior to birth," said Sulmasy. "It would be wonderful if we could do it in a way that was ethical and safe."

Although He — who conducts research at the Southern University of Science and Technology of China — would have a difficult time performing similar gene editing on humans in the U.S., gene editing is not out of the question in America. 

In the U.S., there is a law, known as the Aderholt Amendment, which prohibits the Food and Drug Administration (FDA) from accepting research submissions "in which a human embryo is intentionally created or modified to include a heritable genetic modification." 

But gene editing — although hugely expensive — could be done privately, without federal restrictions. 

"You could probably do it with private money and private doctors," said Caplan. 

Perhaps a billionaire wants genetically-altered kids, noted Gronostajski. "It's possible they would find someone who would do it," he said. 

This might be done at a fertility clinic, as clinics provide medical treatment, not research. And in the United States, "research is much more heavily regulated in the U.S. than [treatment] in medical practices," Gronostajski said. 

All of this adds up to the global scientific (and perhaps political) community needing to view gene editing not as a futuristic thought exercise, but a certain reality with uncertain results. 

"It's time to get some international agreements," said Caplan.

"It was anticipated that someone would eventually want to edit human beings," noted Gronostajski. "It's a wake-up call."

There is, of course, the chance that He has not accomplished what he's claiming to have done. Although the notion of an elaborate hoax is growing more unlikely, it's still a possibility, at least until He reveals more information. 

"The world has been burned before," said Sulmasy, noting that medical scientists have made bogus or largely misleading claims before.

On Wednesday, He announced that he had submitted his research to an academic journal where it can be vetted by experts, but he did not reveal which journal. 

It's uncertain what exactly the Chinese position is on human gene-editing. Over 100 Chinese scientists formally expressed outraged over the human experiment, and He's university has ordered an investigation.  

"It's not clear who signed off on this experiment," said Caplan. "The Chinese position needs to be clarified."

Whatever He's scientific fate, the fate of two girls has likely already been rewritten, in their genes, anyhow.

Scientists will certainly be watching as the newly-coded genes continue to manifest, potentially in unpredictable or harmful ways. 

 "We won’t know the results of that experiment for at least 30 years," said Gronostajski.

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