http://www.digitaljournal.com/tech-and-science/science/crispr-trial-sets-out-to-cure-human-blindness/article/555046

CRISPR trial sets out to cure human blindness

Posted Jul 31, 2019 by Tim Sandle
The next-step with the progression of the gene editing tool CRISPR is to be with non-genetic diseases, based on a new phase where the technology can be used to edit single letters in RNA. One application is to attempt to find a cure for blindness.
Siaka Coulibaly  a resident of Djibi village  suffers from health problems  including blindness  cau...
Siaka Coulibaly, a resident of Djibi village, suffers from health problems, including blindness, caused by the 2006 dumping of toxic waste by the Probo Koala ship in the Ivory Coast
Issouf Sanogo, AFP/File
Specifically, CRISPR will be tested out as a treatment for a form of blindness termed Leber congenital amaurosis. This form of blindness refers to a family of congenital retinal dystrophies that results in severe vision loss at an early age. The condition affects about 1 in 80,000 people and is the most common form of inherited sight loss in children.
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The treatment has been approved by the U.S. Food and Drug Administration (FDA), and the application of CRISPR for this purpose will represent the first time such a treatment will be trialed in the U.S.
CRISPR -  revolutionary new tool to cut and splice DNA.
CRISPR - revolutionary new tool to cut and splice DNA.
Illustration courtesy of Jennifer Doudna/UC Berkeley
What is CRISPR?
CRISPR (an acronym for Clustered regularly-interspaced short palindromic repeats), as Digital Journal has reported (see the article: "Is CRISPR technology set to change biological science?”), is a type of biological cut-and-paste technology. This technique permits scientists to detect a gene defect within living cells and then use molecular “scissors” to make genetic adjustments, like deleting the gene; repairing it; or completely replacing it. It should be noted that the side effects and reactions still remain unclear at this point.
Developing the new procedure
With the new procedure, researchers from Editas Medicine will attach a synthesized sequence of guide RNA, which will match a target DNA sequence, to the enzyme Cas-9. This will be introduced into a cell’s nucleus. As soon as the matching DNA sequence is located, the Cas-9 enzyme will snip the DNA strand, and then cell will activate to repairs the cut. The procedure will focus on the mutations most commonly responsible for Leber congenital amaurosis. These are known to occur in the CEP290, CRB1, GUCY2D, and RPE65 genes.
As for the patent, this could be as simple as an operation where some gel-like tissue within the eyes is removed, patients and then the treatment is injected behind each retina. The trial will evaluate whether the DNA then repair itself so that it restores normal protein function. Through this the process could fix the photoreceptor cells and result in the patent being able to see again.
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The new study will test children from three years and up, plus adults, all with varying degrees of vision.