PUBLIC RELEASE DATE:

30-Mar-2014

Contact: Sarah McDonnell s_mcd@mit.edu 617-253-8923 Massachusetts Institute of Technology

CAMBRIDGE, MA -- Using a new gene-editing system based on bacterial proteins, MIT researchers have cured mice of a rare liver disorder caused by a single genetic mutation.

The findings, described in the March 30 issue of Nature Biotechnology, offer the first evidence that this gene-editing technique, known as CRISPR, can reverse disease symptoms in living animals. CRISPR, which offers an easy way to snip out mutated DNA and replace it with the correct sequence, holds potential for treating many genetic disorders, according to the research team.

"What's exciting about this approach is that we can actually correct a defective gene in a living adult animal," says Daniel Anderson, the Samuel A. Goldblith Associate Professor of Chemical Engineering at MIT, a member of the Koch Institute for Integrative Cancer Research, and the senior author of the paper.

The recently developed CRISPR system relies on cellular machinery that bacteria use to defend themselves from viral infection. Researchers have copied this cellular system to create gene-editing complexes that include a DNA-cutting enzyme called Cas9 bound to a short RNA guide strand that is programmed to bind to a specific genome sequence, telling Cas9 where to make its cut.

At the same time, the researchers also deliver a DNA template strand. When the cell repairs the damage produced by Cas9, it copies from the template, introducing new genetic material into the genome. Scientists envision that this kind of genome editing could one day help treat diseases such as hemophilia, Huntington's disease, and others that are caused by single mutations.

Scientists have developed other gene-editing systems based on DNA-slicing enzymes, also known as nucleases, but those complexes can be expensive and difficult to assemble.

"The CRISPR system is very easy to configure and customize," says Anderson, who is also a member of MIT's Institute for Medical Engineering and Science. He adds that other systems "can potentially be used in a similar way to the CRISPR system, but with those it is much harder to make a nuclease that's specific to your target of interest."

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Erasing a genetic mutation