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article imageWhat you need to know about gene editing success in U.S.

By Tim Sandle     Jan 1, 2016 in Science
New York - Scientists have successfully used gene editing techniques to treat mice with the genetic condition Duchenne muscular dystrophy.
Duchenne muscular dystrophy is an inherited genetic disease, affecting around one in 3,600 boys. The condition leads to progressive muscle degeneration and premature death and it is the result of a gene mutation. The defective gene leads to an error with the protein that codes for dystrophin. Dystrophin is an important component within muscle tissue.
Duke University researchers have used the technique CRISPR-Cas9 to delete DNA that was interfering with cells and preventing them from producing dystrophin. CRISPR is an acronym for Clustered regularly-interspaced short palindromic repeats (it is pronounced "crisper".) CRISPR are segments of microbial DNA containing short repetitions of base sequences. Each repetition is followed by short segments of "spacer DNA," which is the result of previous exposures to a bacterial virus. A CRISPR can provide a form of acquired immunity.
With CRISPR-Cas9, the synthetic DNA is combined with a protein called Cas9. The protein functions to splice up DNA in the host. The video below explains the process in more detail:
https://www.youtube.com/watch?v=2pp17E4E-O8
With the new study, a virus was used to deliver DNA alterations into the cells of mice (with mice bred to have the Duchenne muscular dystrophy condition.) The therapeutic product was injected directly into the legs of adult mice, and improvement in muscle strength was rapidly seen. Moreover, when the compound was injected into blood, improvement with heart muscle were observed.
Speaking with the BBC, one of the lead researchers, Chris Nelson stated: "A major hurdle for gene editing is delivery. We know what genes need to be fixed for certain diseases, but getting the gene editing tools where they need to go is a huge challenge. The best way we have to do it right now is to take advantage of viruses, because they have spent billions of years evolving to figure out how to get their own viral genes into cells."
The long-term aim is to move onto human trials.
The pioneering research is reported to the journal Science, in a paper titled "In vivo genome editing improves muscle function in a mouse model of Duchenne muscular dystrophy."
A second study has looked at gene editing in mouse egg and sperm cells of mice carrying Duchenne muscular dystrophy. This has produced an 80 percent success rate. This type of study, altering the germline, is seen as more controversial. This study is also published in Science ("In vivo gene editing in dystrophic mouse muscle and muscle stem cells.")
More about Gene editing, Duchenne muscular dystrophy, Genes, Genetics
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