The Scientist reports:

While researchers have found plenty of gene variants that seem to increase the risk of an autism diagnosis, it’s not clear why some people carrying these mutations develop autism spectrum disorders and some do not. In a study published today (September 17) in Science Advances, researchers point to a potential answer: severe infections during early childhood. After an early immune challenge, male mice with a mutated copy of the tuberous sclerosis complex 2 (Tsc2) gene developed deficits in social behavior linked to changes in microglia, the immune cells of the brain. And an analysis of the hospital records of more than 3 million children showed that children, particularly boys, who were hospitalized for infections between ages 18 months and four years were more likely that healthy peers to receive a future autism spectrum disorder (ASD) diagnosis.

“We have genetic models, and we have a lot of in utero exposure models and early life stress models, but it’s pretty rare that people are blending the two to find that gene [and] environment interaction,” says Audrey Brumback, a pediatric neurologist at the University of Texas at Austin Dell Medical School who was not involved in the work. Plus, “we’re so neuron centric in neuroscience, [but] a huge chunk of our brain is non-neuronal,” she adds. “It’s really exciting to see work that’s exploring those non-neuronal cells.”

“We knew that mutations predispose [people] for autism, but if you look in patients with genetic mutations, not everyone with that mutation has autism, and the question is why?” says neuroscientist Alcino Silva of University of California, Los Angeles (UCLA). One such type of mutation, linked to autism in about half of the people who carry the variants, are in the tuberous sclerosis complex 1 or 2 genes and can have a range of symptoms in addition to autism. Mice with a mutation in Tsc2 have some of the same symptoms, but until about a decade ago, the social deficits that can show up in people with the mutations had not been recreated in the mouse model. Then, in 2010, Silva’s group showed that challenging the immune systems of pregnant mice caused ASD-like behavior in their Tsc2 mutant offspring. [Continue reading…]