Doctors edit genes inside body for blindness

open up a whole new set of medicines to go in and change your DNA.”

Dr. Jason Comander, an eye surgeon at Massachusetts Eye and Ear in Boston, another hospital that plans to enroll patients in the study, said it marks “a new era in medicine” using a technology that “makes editing DNA much easier and much more effective.”

Doctors first tried in-the-body gene editing in 2017 for a different inherited disease using a tool called zinc fingers. Many scientists believe CRISPR is a much easier tool for locating and cutting DNA at a specific spot, so interest in the new research is very high.

The people in this study have Leber congenital amaurosis, caused by a gene mutation that keeps the body from making a protein needed to convert light into signals to the brain, which enables sight. They’re often born with little vision and can lose even that within a few years.

Scientists can’t treat it with standard gene therapy — supplying a replacement gene — because the one needed is too big to fit inside the disabled viruses that are used to ferry it into cells.

So they’re aiming to edit, or delete the mutation by making two cuts on either side of it. The hope is that the ends of DNA will reconnect and allow the gene to work as it should.

It’s done in an hourlong surgery under general anesthesia. Through a tube the width of a hair, doctors drip three drops of fluid containing the gene-editing machinery just beneath the retina, the lining at the back of the eye that contains the light-sensing cells.

“Once the cell is edited, it’s permanent and that cell will persist hopefully for the life of the patient,” because these cells don’t divide, said one study leader not involved in this first case,

Dr. Eric Pierce at Massachusetts Eye and Ear.

Doctors think they need to fix onetenth to one-third of the cells to restore vision. In animal tests, scientists were able to correct half of the cells with the treatment, Albright said.

The eye surgery itself poses little risk, doctors say. Infections and bleeding are relatively rare complications.

One of the biggest potential risks from gene editing is that CRISPR could make unintended changes in other genes, but the companies have done a lot to minimize that and to ensure that the treatment cuts only where it’s intended to, Pierce said. He has consulted for Editas and helped test a gene therapy, Luxturna, that’s sold for a different type of inherited blindness.

Some independent experts were