Primate models could be especially helpful to researchers trying to make sense of the growing number of mutations that genetic studies have linked to brain disorders. The significance of a specific genetic variant is often unclear; it could be a cause of a disorder, or it could just be indirectly associated with the disease. CRISPR could help researchers tease out the mutations that actually cause the disorders: they would be able to systematically introduce the suspected genetic variants into monkeys and observe the results. CRISPR is also useful because it allows scientists to create animals with different combinations of mutations, in order to assess which ones—or which combinations of them—matter most in causing disease. This complex level of manipulation is nearly impossible with other methods.
Scientists in Kunming, the capital of China’s Yunnan province, have just carried out a breakthrough experiment, which some may consider highly controversial. They created a pair of macaque monkeys with genetic mutations hoping to provide a new path for studying brain disorders. The mutations were inserted into the fertilized eggs in vitro, using the CRISPR (Cluster Regularly Interspaced Short Palindromic Repeats) /cas9 technique, and then transferred into a surrogate.
In brief, The CRISPR/cas9 is a new genome-editing tool that was proven to work back in 2005 with a plethora of organisms ranging from prokaryotes to eukaryotes. This technique of gene modification allows for extreme accuracy of gene insertion or deletion on chromosomes, and was just recently proven to work with human cells in 2012.
CRISPR has the potential to be a powerful therapeutic tool and the fact that Chinese scientists have already used it to insert genes into primates gives reason to believe that human testing is the end goal, but we wont be seeing that for a while. For now the scientists are still figuring out all the ways that the monkeys could be used to study brain diseases. Many experiments with psychiatric drugs in the past that have worked well with mice have failed in humans. Scientists hope that the primate model will provide us with more relevant studies and hopefully one-day lead us to precisely alter DNA at the embryonic stage.
Creating monkeys with psychological diseases brings up a lot of ethical issues, but it could produce a lot of valuable research as to understanding the development of diseases like Parkinson’s and autism. Although these experiments are still in the very early stages, the accuracy of the new CRISPR techniques will no doubt accelerate the research. As we continue to discover what genes code for which diseases we will be able to engineer the genes into other organisms and do accurate testing.
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