While many different combinations of genetic traits can cause autism, brains affected by autism share a pattern of ramped-up immune responses, an analysis of data from autopsied human brains reveals. The study included data from 72 autism and control brains. It will be published in Nature Communications.
“There are many different ways of getting autism, but we found that they all have the same downstream effect,” says Dan Arking, Ph.D. , an associate professor in the McKusick-Nathans Institute for Genetic Medicine at the Johns Hopkins University School of Medicine. “What we don’t know is whether this immune response is making things better in the short term and worse in the long term.”
The causes of autism, also known as autistic spectrum disorder, remain largely unknown and are a frequent research topic for geneticists and neuroscientists. But Arking had noticed that for autism, studies of whether and how much genes were being used, known as gene expression, had thus far involved too little data to draw many useful conclusions. That’s because unlike a genetic test, which can be done using nearly any cells in the body, gene expression testing has to be performed on the specific tissue of interest, in this case, brains that could only be obtained through autopsies.
To combat this problem, Arking and his colleagues analyzed gene expression in samples from two different tissue banks, comparing gene expression in people with autism to that in controls without the condition. All told, they analyzed data from 104 brain samples from 72 individuals, the largest data set so far for a study of gene expression in autism.