The Genetic Reason Why Autistic People Repeat Themselves

Scientists have linked many genes to autism — largely to the chances of developing autism. However, researchers now suspect that there are risk genes driving specific autism symptoms, including repetitive behaviors.

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

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. Although 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 autistic individuals, 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 treating behavioral symptoms of autism in the future. That’s promising news that, ironically, bears repeating.