A new improved gene therapy?

As written in one of the previous posts, treating neurodegenerative diseases with RNAi is more difficult than treating hepatitis C or other similar diseases. However, a new study on the neurodegenerative disease Machado-Joseph, shows that an improved gene therapy is being tested.
What is Machado-Joseph disease and why is it important?
Finding a cure for Machado-Joseph disease is important because at present it is untreatable. The disease is characterized by progressive motor discoordination that could, eventually, lead to death.
The MJD1 gene is responsible for the production of ataxin-3 ---a brain protein alleged to be useful in the destruction of toxic proteins in the brain. However, the mutated MJD1 gene is not able to produce functional ataxin-3 protein. The mutated ataxin-3 protein then accumulates in the brain and causes neural damage.
This research conducted by Alves, Almeida, Déglon et al. from the Center for Neurosciences & Cell Biology at the University of Coimbra, Portugal and the Institute of Molecular Imaging and Molecular Imaging Research Center in Orsay, France have found an improved way to silence the MJD1 mutated gene and potentially treat Machado-Joseph disease.
Nevertheless, how exactly is this different from any other studies? Even though the study still uses RNAi to silence the gene, these researchers have improved their targeting precision. Remember, that there are usually two copies of a gene--- the mutated and the normal gene. Therefore, if only one gene is mutated and the other MJD1 gene is still producing normal ataxin-3, it would be deleterious to silence both the mutated and normal MJD1 gene.
The improved RNAi has been tested on infected rats with the neurodegenerative disease. The study showed that the RNAi led to a decrease of approximately 50% of the mutated proteins accumulated in the brain of a live animal.
However, we must keep in mind that even though these results are promising, they are promising in rats. Further research has to be done before moving to clinical trials. On the bright side, the RNAi treatment did not cause any side effects in the tested rats; therefore, decreasing the possibility of having serious side effects in humans. In conclusion, this experiment provides hope that one day RNAi will be used to treat neurodegenerative diseases by silencing the mutated gene and not the normal gene that can still be useful in the brain.
For more information, check out: http://www.innovations-report.com/html/reports/life_sciences/a_improved_gene_therapy_treatment_machado_joseph_119799.html