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The gene edition is advancing at a faster pace than most of us can follow. The application of the CRISPR gene modification tool to non-genetic diseases through a new ability to modify unique letters in RNA has recently been announced.
Even though CRISPR is taking such steps, scientists continue to find new uses for CRISPR to treat genetic diseases. The next treatment proposed in the clinics is a CRISPR treatment for a form of blindness called Leber Conbad Amaurosis (CLA).
After being approved by the FDA in December, the treatment will be the first of its kind to be tested in the United States.
What is LCA?
ACV is a group of inherited disorders that cause severe vision loss at birth. Both parents must have a defective gene for the disease to inherit; 2-3 babies in 100,000 are born with stroke.
The disease can be caused by mutations of at least 14 different genes that play a role in the development of the retina (the layer of nerve cells located at the back of the eye that detects light and sends signals to the brain), affecting the two peripheral rods. cells – which help in low light vision – and central cone cells, which are essential for seeing details and colors.
The pupils of people with stroke do not react normally to light, do not expand or contract under the effect of the amount of light entering the eye. For example, in one version of the disease, a mutation in the gene responsible for vitamin A metabolism reduces the ability of photoreceptors (nerve cells specialized in the retina) to send visual information to the brain and causes premature death of photoreceptor cells.
How CRISPR would correct it
As part of the CRISPR gene editing, scientists badociate a synthesized sequence of guide RNA corresponding to the target DNA sequence to the Cas-9 enzyme and introduce it. in the nucleus of a cell. When the corresponding DNA sequence is localized, Case-9 cuts the DNA strand and the cell then repairs the cut.
The most commonly occurring mutations of ACL occur in the CEP290, CRB1, GUCY2D and RPE65 genes. In type 10 ACL, a CEP290 mutation causes dysfunction of a protein that contributes to the formation of photoreceptor cells in the retina.
After removing some of the gel-like tissue from their eyes, the treatment will be injected to the patients behind their retina. The hope is that patients' DNA is repaired in ways that restore normal protein function, by finally fixing their photoreceptor cells and allowing them to see.
The treatment will be administered by Editas Medicine of Cambridge and its pharmaceutical partner Allergan in Dublin.
Look back, look forward
This is the first study to use CRISPR to modify DNA in the human body, but this is not the first time that CRISPR-based medicine has been tested in humans, or the first time that gene therapy is used to treat stroke.
CRISPR was used for the first time in the United States this year, when doctors at the University of Pennsylvania badociated it with anti-cancer CAR-T treatment to treat two patients (treatment results did not occur). have not yet been published). .
In late 2017, the FDA approved a gene therapy called Luxturna to treat LCA2, a form of the disease caused by a mutation of a gene different from the one involved in type 10. It was a the first gene therapy directly administered for an inherited disease. approved in the United States. Only one other company, Sangamo Therapeutics, has tried gene editing in the body to treat metabolic diseases using a tool called zinc fingers.
The difference between LCA2 treatment and the treatment that will be given to LCA10 patients is that Luxturna inserts a healthy copy of the defective gene directly into the retinal cells, while CRISPR locates the defective gene on the DNA strand and cuts it at the same time. good time. , and allows him to repair himself.
Although nothing guarantees CRISPR treatment for stroke, it is very promising; Luxturna was able to improve the vision of its recipients without any known side effects, and a similar trial in the Netherlands resulted in improved vision in about 60% of participants.
Treatment should begin this fall in 18 children and adults and last up to 3 years.
Image Credit: sie_horton / Shutterstock.com
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