Faulty immune cells in the developing brain may contribute to autism

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A recent study in mice investigates immune cells called microglia in the developing brain. The authors conclude that the failure of these cells to perform an essential housekeeping role may lead to autism spectrum disorder in boys.

A recent study looks at microglia and autism spectrum disorder.
Children with autism spectrum disorder (ASD) often display impaired social functioning, repetitive and inflexible behavior, and hypersensitivity to sound and light.
Among 8-year-olds in the United States, about 1 in 59 (1.7%) has ASD.

However, research suggests that boys are four times more likely than girls to develop the disorder. About 2.7% of boys and 0.7% of girls have ASD.

Why males are more susceptible than females has been a subject of debate among scientists, but a new study suggests that brain cells called microglia may be partly to blame.

One of the functions of microglial cells in the developing brain is to engulf or “prune” redundant synapses. Synapses are the electrical connections between nerve cells.

Neuroscientists believe that synaptic pruning is essential for young brains to maintain their flexibility or “plasticity.”

Overproduction of proteinResearch in mice has now found that the overproduction of protein in microglia — as a result of a genetic fault — prevents the cells from performing this vital housekeeping role, but only in males.

Male mice with this genetic quirk in their microglia display autism-like impairments in social skills and behaviors.

This suggests that in some boys, the overproduction of protein in microglia during brain development may contribute to ASD.

The research, which features in Nature Communications, was a collaboration between neuroscientists at Scripps Research in Jupiter, FL, and those at the Korea Brain Research Institute in Daegu, South Korea.

“Our study suggests that impairments in microglia play a key role in the development of autism behaviors, at least in some cases, and may help explain the higher prevalence of autism disorders in males,” says senior study author Prof. Baoji Xu, Ph.D., of Scripps Research.

Gene variants Scientists have linked hundreds of gene variants to ASD, but individually, they only raise the risk of developing the condition by a tiny amount. Some of these genes are inherited, while others are the result of new mutations.