For decades, people have heard that gene therapy will someday replace treatment for many genetic diseases, but, thus far, the public has seen few of these claims come to fruition. However, Crispr (Clustered regularly interspaced palindromic repeats) may change all of that. Crispr is the bacterial equivalent of an immune system. It recognizes repetitive sequences in an attacking viral genome, and cuts its DNA, thereby destroying the virus. So essentially Crispr is a saw and guide system that specific DNA sequences act as the guides. Scientists can usurp these guides to utilize the saw for genetic manipulation. This is great news on the gene therapy front.
Most methods of gene therapy to date involve viral introduction of beneficial genes. This method is limited as introduction to the cell is inconsistent and it can only help individuals whose disease results from a lack of the proper gene product. It is useless for individuals with a dominant, harmful gene product, such as Huntington’s disease (http://en.wikipedia.org/wiki/Huntington%27s_disease). Crispr on the other hand introduces changes to your own DNA. This means damaging mutations could be turned off or corrected.
This may sound similar to systems developed using zinc finger nucleases (ZFN), some of which are already in clinical trials (http://www.nejm.org/doi/full/10.1056/NEJMoa1300662). However, the ZFN system requires a new protein for each targeted change. This is cumbersome and time consuming. Why? Well to go back to our woodworking example, researchers basically have to invent a new specialty saw for each project. Crispr only requires its guides to be placed on each new piece for it to work. Even better, you could place multiple guides and make more than one cut per attempt. This means people with multi-gene diseases could have a therapy that treats multiple issues in one foul swoop. So keep your eye out for Crispr, it could be the new saw in the doctors’ workshop.
For more information on Crispr see:
DNA Aficionado 