While the monkeys mimicked the autism symptoms of humans better than any mouse models of the past, the altered primates didn’t show the severity of symptoms seen in autistic patients, Alysson Muotri, an autism and Rett syndrome researcher at the University of California, San Diego, told Nature. In addition, researchers found the monkeys passed on the gene and the resulting symptoms to their offspring – possibly proving an avenue for research into the genetics of autism.
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Five transgenic monkeys have become the first nonhuman primates to show signs of autism. Duplications of the MeCP2 gene in humans is associated with autism-like symptoms, and 90 percent of patients Rett syndrome have been found to have mutations in the MeCP2 gene. But, with the complexity of the disease in humans and the simplicity of the similar behaviors observed in the monkeys, some researchers are leery about how useful the animals will be in autism research.
Normally, monkeys sit together and groom each other, but the transgenic monkeys in the study were less socially engaged. “The transgenic monkeys showed less interaction with wild-type monkeys within the same group, and also a reduced interaction time when paired with other transgenic monkeys in social interaction tests”. “We think it provides a very unique model”. “But mice have very different brains from our own”.
The study researchers said it was hard to give an exact cost figure, since these experiments require hundreds of monkeys across multiple institutions.
The research was conducted in China and led by Prof Zilong Qiu of the Institute of Neuroscience, Shanghai and colleagues. More typical symptoms like seizures were absent, she said, while the monkeys’ circling doesn’t have an analog in humans. After being fertilized, the eggs were inserted in surrogate monkeys and resulted in 8 specimens, each of them carrying the gene. “For the sake of the field and the families it is important that we study models that are constructed to genetically mimic what happens in humans and that reproduce features of the syndrome as closely as possible”, Zoghbi says, reports MIT Technology Review. Next, the researchers plan to use the CRISPR gene-editing technique to knock out the extra MECP2 copies in cells in those regions and then check whether the autisim-like symptoms stop. But this still wasn’t enough to be sure that the monkeys were a sound model of autism – and a paper that the team submitted for publication in 2013 was rejected.
One of the disagreements involves the effectiveness of using monkeys to model human brain disorders.
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“This excellent research has developed a more sophisticated model of autism which may further our understanding of autism, and could eventually lead to the development of more tailored treatments”, said Dr James Cusack of Autistica, an autism medical research charity in Britain. “There is a sentiment that you are never going to generate enough animals to be able to do the really important experiments. I would say the smartest minds in the field say we have got to do this”.
