For the first time, scientists in China have genetically engineered monkeys that carry a human autism gene and develop symptoms similar to people who have the disorder.
The hope, they say, is to better understand autism in humans and potentially develop treatments.
The research, the subject of a paper published this week in the journal Nature, was conducted by a team at the Institute of Neuroscience in Shanghai. Until now, animal research into autism has relied on lab mice, which the MIT Technical Review says has provided "disappointingly few leads on how to solve the problem in people," because of vast differences in human and mice brains.
The Chinese scientists created special test-tube monkeys for the research. They attached MECP2 genes -- thought to be linked to autism in humans -- to a harmless virus, which they then injected into the eggs of macaque monkeys. The eggs were then fertilized and implanted into female monkeys.
At around 11 months of age, the transgenic offspring began showing asocial behavior, including pacing in circles and becoming stressed when looked in the eyes.
"As compared to the wild type monkeys, MECP2 transgenic monkeys gained weight more slowly, had fatty acid metabolism abnormalities, exhibited a higher frequency of repetitive circular locomotion and showed increased stress responses in threat-related anxiety tests," lead researcher Zilong Qiu wrote.
"Most importantly, the transgenic monkeys showed less social interaction time with wild-type monkeys and also a reduced interaction time when paired with other transgenic monkeys in social interaction tests."
Autism is a group of complex disorders of brain development characterized, in varying degrees, by difficulties with social interaction, verbal and nonverbal communication and repetitive behaviors, according to Autism Speaks.
Centers for Disease Control and Prevention statistics show that 1 in 68 children is on the autism spectrum, and that autism is nearly five times more common in boys than girls.
Some critics have raised ethical questions about the new research on monkeys. Others hailed the development. University of California psychiatry professor Melissa Bauman said the work “opens the possibility to explore genetic risk factors in a species more closely related to humans.”
The study authors said their findings "pave the way for the efficient use of genetically engineered macaque monkeys for studying brain disorders.”
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