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Researchers Use CRISPR To Repair Genetic Defect That Causes Blindness (dispatchtribunal.com)
hypnosec writes: In what has been claimed to be the first use of gene editing technique CRISPR for replacement of a defective gene associated with a sensory disease, researchers have repaired a genetic defect that causes blindness. The research that led to successful editing of defective genes responsible for retinitis pigmentosa (RP) – an inherited condition that causes the retina to degrade and leads to blindness in at least 1.5 million cases worldwide – was carried out using stem cells derived from a patient's tissue. Published in Scientific Reports, the study paves the way for using CRIPSR therapeutically to treat eye diseases.
The whole point of using GMO technology in an application like this is the 'exceptional specificity' cited in the article.
"The primary advantage of CRISPR over previous technologies is the ability to use a genetic scalpel rather than a sledgehammer," said Charles Gersbach, associate professor of biomedical engineering at Duke University.
How can there be side effects if the only modification is changing a specific already damaged gene back to it's known healthy setting?
If you are just stabbing around changing random stuff sure there will be random consequences.
But if you can change specific genes and you know what the damaged state and the healthy states are, you are good to go.
The article you reference does not demonstrate any side effects.
However, it is a valid concern, in that in vitro CRISPR/CAS9 and CRISPR/CPF1 edits has historically hit identical palindromic sequences that happened to be outside the target edit area, since the palindromes in question are only 24 or so base pairs in length. You have to expect that there will be other instances elsewhere in the genome.
If you read the article, the experiment was conducted on pluripotent stem cells created from skin cells taken from the patient, and done in vitro.
The eventual hope in this case is implantation of the in vitro stem cells in order to correct the defect.
This means that any side effects can be avoid by separating the edited cells into individual cells, and then culturing each batch to the point some of the batch can be taken and fully sequenced to verify that the only change in the gene sequences relative to the (fully sequenced) parent organisms genome, is the target gene sequence alone. This would be done before implantation, which would guarantee that the gene sequence causing the disease was the only one impacted by the therapy.
Practically speaking, we have AAVV/AAV-2 techniques -- utilizing Adeno-associated virus vectors, in other words -- that tend to be much more accurate. This is the type of vector that was utilized by the CEO of BioViva, Elizabeth "Liz" Parrish:
https://www.youtube.com/watch?...