Researchers are harnessing genetic engineering tools in an effort to restore sight to people who suffer from inheritable conditions.
Consider Leber congenital amaurosis, a genetic eye disease that afflicts approximately 2 to 3 out of every 100,000 newborn children, according to the U.S. National Library of Medicine, which notes it is among the most common reasons people become blind in childhood.
“Leber congenital amaurosis is an eye disorder that primarily affects the retina, which is the specialized tissue at the back of the eye that detects light and color.”
Usually, the result is severe visual impairment from infancy that tends to remain stable. However, some children will experience that their impairment increases at a very slow rate.
Because individuals with Leber congenital amaurosis cannot see very well, scientists are interested in experimenting with CRISPR gene editing.
Experimental CRISPR Gene Editing for Restoring Vision
Leber congenital amaurosis (LCA) is a progressive disease that NPR says “disables crucial cells in the retina.” People with LCA are typically deemed to be legally blind. So, they often must rely on others to drive them and may find it hard to navigate while walking.
Enter Dr. Mark Pennesi. He is a professor of ophthalmology at the Casey Eye Institute at the Oregon Health & Science University and has been running experiments with CRISPR to combat LCA. He recently presented the latest results of CRISPR tests in Nashville, Tenn., at the International Symposium on Retinal Degeneration.
His team ran a CRISPR experiment on seven patients with LCA. One of them, Carlene Knight, found it challenging to use a cane while maneuvering around at her job in a call center.
She has had a visual impairment since birth. The doctors at the Casey Eye Institute made genetic changes to a virus, which they used to deliver the CRISPR gene editing tool. They infused modified viruses (by the billions) into the retina of Knight’s left eye (and to the retinas of 6 other patients during this particular experiment).
Doctors only wanted to test CRISPR in one eye of each patient, so they would have one eye left if something went awry with the retina being treated.
The goal was to see if the CRISPR modification carried by the modified viruses would find and remove genetic mutations in the patients’ retinas. After CRISPR made its way inside the retina cells, the hope was that dormant cells would reactivate, bringing vision back to those with impairments from LCA.
Fortunately, the experiment has yielded some good initial results. Since participating in the Casey Eye Institute study, Knight can now see objects and identify colors, find doorways and make her way through hallways, per NPR.
Not every patient in this particular study had vision improvement. This may be due to them receiving different amounts of genetically modified viruses or because their visual impairment was severe.
Harnessing CRISPR to Treat A Range of Diseases
The Oregon Health & Science University researchers who are testing genetic modifications to restore sight point out that they need to conduct more tests and studies to see how they might improve the results.
Oregon’s work is just one example of how scientists are opening up the frontier of healing people who have problems with their DNA. Ongoing work with CRISPR is occurring with beta-thalassemia and sickle cell anemia, for example.
So, people with genetic disorder illnesses that currently have no treatment will want to stay on top of developments by scientists who are experimenting with CRISPR gene editing. Another new treatment could be just around the corner.
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