"Genetically modified (GM) monkeys that develop symptoms of autism have been created to help scientists discover treatments for the condition," The Guardian reports.
The reports are based on news that Chinese researchers have created monkeys with autistic traits using gene editing techniques.
The monkeys were modified to possess the human gene MECP2. Mutations in this gene or carrying too many copies of the gene in humans has been linked to autistic spectrum disorder (ASD). ASD affects social interaction, communication, interests and behaviour.
The researchers wanted to test whether the genetically modified monkeys would show autism-like behaviours and if they were able to pass this gene on to their offspring.
The researchers found that the modified monkeys did show certain autism-like behaviours. These included increased frequency of repetitive movement in a circle, increased anxiety and reduced social interaction.
Tests showed that sperm from one of the modified monkeys could be used to produce offspring which also carried the MECP2 gene. These offspring also showed reduced social interaction.
Previous animal studies into ASD have mainly relied on rodents, so the hope is that the more human-like monkeys will provide a greater insight into the condition and possibly lead to new treatments.
The news that researchers have, seemingly, created "autistic monkeys" has been met with a mixed reaction by other experts working in the ASD field.
Professor Roger Lemon, Sobell Chair of Neurophysiology at University College London, welcomed the news and is quoted by the Science Media Centre as saying, "I think this is a potentially very important scientific development. Given the widespread incidence of autism in humans, and some of its debilitating side effects, important clinical insights could also result from this new transgenic model."
Other experts were less enthusiastic. Professor David Skuse, also at University College London, is quoted by the New Scientist as saying, "The question is: if you create an animal model based on a human genetic anomaly, what does that tell you about autism in general? I don't think it necessarily tells you anything about autism."
The study was carried out by researchers from the Chinese Academy of Sciences and Fundan University.
Funding was provided by the CAS Strategic Priority Research Program, the MoST 973 Program, NSFC grants, the National Key Technology R&D Program of China, and the Shanghai City Committee of Science and Technology Project.
Generally, this study has been reported accurately by the UK media, accompanied by an explanation of the potentially important role of monkeys in advancing medical research.
This is an animal study on monkeys, with researchers looking at whether they could generate an animal model of ASD.
They did this by genetically modifying monkeys to carry a form of the human MECP2 gene that would be active in their brains. In humans, mutations in this gene cause Rett syndrome – a complex and severe condition, which includes autism spectrum behaviours. People who carry an extra copy of the gene also show symptoms of ASD.
The researchers wanted to generate an animal model of ASD, so they could study the condition and possible treatments with greater ease. Making animal models of complex human conditions such as ASD is very difficult. However, it is hoped that they can give an early indication of whether a new drug or treatment might hold some promise for human use.
Animal studies are often used to study disease processes and treatments.
This study genetically modified monkeys to carry a form of the MECP2 gene (called the "transgenic" group) which would be active in the monkeys' brains. The researchers compared the genetically modified monkeys with similarly aged non-genetically modified monkeys for the following behaviours:
The researchers also investigated whether the genetically modified monkeys could pass the human gene on to their offspring. If the monkeys did pass on the gene, the researchers could continue to study these transgenic monkeys' offspring without having to genetically modify new monkeys continuously.
It was found that the genetically modified monkeys showed some autism-like behaviours.
The transgenic monkeys spent more time moving in circular patterns than the non-genetically modified monkeys, despite their total time in motion being similar.
The response to the human gaze test found that the total number of anxiety-related grunts made by the transgenic monkeys was significantly higher than that of the non-genetically modified monkeys. Transgenic monkeys were also found to spend less time interacting socially.
The cognitive function tests showed similar findings in both groups of monkeys, including for learning.
The researchers also observed that it is possible for sperm from one of the transgenic monkeys to produce offspring which also carried human copies of the MECP2 gene. The offspring also showed reduced social interaction compared to the non-genetically modified monkeys.
The researchers state that they were able to create monkeys with the human MECP2 gene. These monkeys showed autism-like behaviours, including an increased frequency of repetitive circular motion, increased anxiety and reduced social interaction.
This animal study genetically modified monkeys to carry the MECP2 gene to assess whether they would exhibit autism-like behaviours and pass this gene on to offspring.
The researchers found that the modified monkeys did show some autism-like behaviours, namely an increase in repetitive circular motion, increased anxiety and reduced social interaction.
It has been welcomed by some experts in the field, who feel this is potentially very important and could allow greater understanding of autism. However, as mentioned, other experts have argued that while the research is impressive in terms of technical expertise, studying these types of monkeys may not provide any useful information about autism in humans.
Making animal models of complex human conditions such as ASD is very difficult. This is particularly true when we do not fully understand what causes the condition. In this case, the researchers have used genetic modification to mimic genetic changes in humans that are known to lead to autistic characteristics.
There will be differences between this newly developed animal model and ASD in people. However, researchers hope that studying the monkeys could help in understanding the condition better, and possibly give some early indication of whether new drugs might hold some promise for human use.