The Genetic Reason People With Autism Repeat Themselves

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April is Autism Awareness Month and even MIT scientists are getting in on the action with compelling new genetic research. Past studies have linked several risk genes to autism spectrum disorder (ASD) and also show that ASD involves the complex interaction of many genes. However, researchers now suspect that there are risk genes driving specific autism symptoms, such as repetitive behaviors.

The study, published today in The Journal of Clinical Investigation, looked at an ASD-associated gene known as SHANK3 in mice. SHANK3 might sound like a low-budget prison movie sequel, but it is actually a scaffolding protein that organizes the flow of neurons in the synapses. Researchers found that SHANK3-deficient mice displayed repetitive behaviors, both in regards to grooming and social interactions. This made them a suitable experimental model for studying autism.

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Guoping Feng, a neuroscience professor and lead author of the study, hypothesized that a mutation in SHANK3 affected the synaptic development in two neural pathways, direct and indirect striatal pathways. While there were significant changes in synaptic shape and function seen in neurons in the indirect pathway with a SHANK3 deficiency, the synapses of the direct pathway were less phased. When researchers activated neurons in the indirect pathway, repetitive behaviors diminished. This suggests such symptoms might be a result of imbalances between the pathways.

Past studies have looked at whether basal ganglia dysfunction is behind repetitive behaviors in individuals with autism, but results have been provided little evidence of this and could not conclude an exact cellular mechanism. This new research not only reveals a potential mechanism but also gives scientists a potential target to treat behavioral symptoms of ASD in the future. That’s promising news that, ironically, bears repeating.

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