Doctors use CRISPR for the first time to edit blindness gene

US doctors use CRISPR gene editing tool INSIDE a person’s body to treat a rare form of blindness in a world first

  • Doctors at Casey Eye Institute at Oregon Health & Science have used the CRISPR gene-editing tool inside the human body for the first time 
  • CRISPR is a cutting-edge but controversial tool that snips out faulty bits of DNA and replaces them with healthy ones 
  • The team used it to treat a rare form of rare inherited blindness in the first patient 
  • It’s the first time it’s been used in a human, aside from the gene-editing a scientist did to a pair of twins  in China, to the shock of the science community  
  • Oregon doctors plan to treat 18 children and adults if it seems safe   

Scientists say they have used the gene editing tool CRISPR inside someone’s body for the first time, a new frontier for efforts to operate on DNA, the chemical code of life, to treat diseases.

A patient recently had it done at the Casey Eye Institute at Oregon Health & Science University in Portland for an inherited form of blindness, the companies that make the treatment announced Wednesday. They would not give details on the patient or when the surgery occurred.

It may take up to a month to see if it worked to restore vision. If the first few attempts seem safe, doctors plan to test it on 18 children and adults.

‘We literally have the potential to take people who are essentially blind and make them see,’ said Charles Albright, chief scientific officer at Editas Medicine, the Cambridge, Massachusetts-based company developing the treatment with Dublin-based Allergan. 

‘We think it could open up a whole new set of medicines to go in and change your DNA.’

Dr Mark Pennesi, who leads OHSU’s involvement in the trial (center right) looks on as staff at school’s Casey Eye Institute perform the first-ever in vivo CRISPR gene edit procedure on a patient who had an inherited form of blindness (Kristyna Wentz-Graff/OHSU via AP) 

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. 


The CRISPR gene editing technique is being used an increasing amount in health research because it can change the building blocks of the body.

At a basic level, CRISPR works as a DNA cutting-and-pasting operation.

Technically called CRISPR-Cas9, the process involves sending new strands of DNA and enzymes into organisms to edit their genes. 

In humans, genes act as blueprints for many processes and characteristics in the body – they dictate everything from the colour of your eyes and hair to whether or not you have cancer.  

The components of CRISPR-Cas9 – the DNA sequence and the enzymes needed to implant it – are often sent into the body on the back of a harmless virus so scientists can control where they go.

Cas9 enzymes can then cut strands of DNA, effectively turning off a gene, or remove sections of DNA to be replaced with the CRISPRs, which are new sections sent in to change the gene and have an effect they have been pre-programmed to produce.

But the process is controversial because it could be used to change babies in the womb – initially to treat diseases – but could lead to a rise in ‘designer babies’ as doctors offer ways to change embryos’ DNA. 

Source: Broad Institute 

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 hour-long 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 one tenth 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. 

Dr Andreas Lauer, right, prepares to perform the procedure, which will replace faulty DNA in the unidentified patient’s eye with healthy genes

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 optimistic about the new study.

‘The gene editing approach is really exciting. We need technology that will be able to deal with problems like these large genes,’ said Dr Jean Bennett, a University of Pennsylvania researcher who helped test Luxturna at the Children’s Hospital of Philadelphia.

In one day, she had three calls from families seeking solutions to inherited blindness.

‘It’s a terrible disease,’ she said. ‘Right now they have nothing.’

Dr Kiran Musunuru, another gene editing expert at the University of Pennsylvania, said the treatment seems likely to work, based on tests in human tissue, mice and monkeys.

The gene editing tool stays in the eye and does not travel to other parts of the body, so ‘if something goes wrong, the chance of harm is very small,’ he said. 

‘It makes for a good first step for doing gene editing in the body.’

Although the new study is the first to use CRISPR to edit a gene inside the body, another company, Sangamo Therapeutics, has been testing zinc finger gene editing to treat metabolic diseases.

Other scientists are using CRISPR to edit cells outside the body to try to treat cancer, sickle cell and some other diseases.

All of these studies have been done in the open, with government regulators’ approval, unlike a Chinese scientist’s work that brought international scorn in 2018. He Jiankui used CRISPR to edit embryos at the time of conception to try to make them resistant to infection with the AIDS virus. 

Changes to embryos’ DNA can pass to future generations, unlike the work being done now in adults to treat diseases.

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