Researchers at the Casey Eye Institute at Oregon Health & Science University on Wednesday announced that scientists for the first time used the gene-editing tool CRISPR to edit DNA inside a patient's body, as part of an effort to restore vision to a patient who lost it due to a genetic disorder.  

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How scientists used CRISPR to try to help this man see

The patient has Leber congenital amaurosis, a condition caused by a gene mutation that prevents the body from creating a protein for converting light into brain signals. Patients born with the disease have very little vision and are at risk for losing their vision entirely, according to the Associated Press.

The condition cannot be treated with typical gene therapy, which involves replacing the faulty gene with a working one. Instead, researchers are testing whether they can edit or delete the mutation using CRISPR by making cuts on each side of it. Once edited, researchers  believe the DNA will reconnect, allowing the gene to work properly and giving the patient the ability to see.

"Once the cell is edited, it's permanent and that cell will persist hopefully for the life of the patient," Eric Pierce, director of the Inherited Retinal Disorders Service at Massachusetts Eye and Ear, who is leading a study on the procedure, said.

The process is done during an hour-long surgery in which doctors insert three drops of fluid containing the CRISPR machinery just below the retina.

After several tests in animals, scientists said they have performed the procedure on a patient, but noted that it could take up to a month to see if the procedure restored the patient's vision. If the first handful of attempts appear to be safe, scientists plan to test the procedure on 18 children and adults, according to AP.

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This marks the first time the CRISPR tool has been used to edit DNA still inside a patient's body. In the past, doctors had used CRISPR to treat a small number of cancer patients and patients with rare blood disorders by removing the cells from the patients' bodies, editing them with CRISPR in a lab, and injecting the cells back into the patient, according to NPR's "Shots."

NIH Director Francis Collins called the news "a significant moment."

"All of us dream that a time might be coming where we could apply this approach for thousands of diseases," Collins said. "This is the first time that's being tried in a human being. And it gives us hope that we could extend that to lots of other diseases—if it works and if it's safe."

Charles Albright, chief scientific officer at Editas Medicine, the company developing the treatment alongside Allergan, said, "We literally have the potential to take people who are essentially blind and make them see. We think it could open up a whole new set of medicines to go in and change your DNA."

Still, both Pierce and Albright emphasized that only one patient had been treated in the study so far and that the research has primarily been designed to determine whether the procedure is safe.

"CRISPR has never been used directly inside a patient before," Pierce said. "We want to make sure we're doing it right."

Pierce added that if the procedure can be done safely, "that opens the possibility to treat many other diseases where it's not possible to remove the cells from the body and do the treatment outside." Pierce said, "We're helping open, potentially, an era of gene-editing for therapeutic use that could have impact in many aspects of medicine."

Artur Cideciyan, a professor of ophthalmology at the University of Pennsylvania, said that since the retina is easy to access, "[i]nherited retinal diseases are a good choice in terms of gene-based therapies."

However, he added that other therapies for retinal diseases are promising, and that it's not yet clear which therapy is best. "The gene-editing approach is hypothesized to be a 'forever fix,'" he said. "However, that's not known. And the data will have to be evaluated to see the durability of that. We'll have to see what happens" (Marchinoe, AP/STAT News, 3/4; Stein, "Shots," NPR, 3/4).