Genetic Basis Of Autism Spectrum Disorder

Scientists have taken another big step toward identifying the genetic flaws which may cause autism, a type of neurological development disorder. In the latest development, laboratory mice have been genetically engineered to produce autism-like behaviors. Researchers have known that certain genetic defects are associated with autism. One of the most common is known as a deletion, when a child inherits only one gene or group of genes, instead of the normally inherited pair, one from each parent.

In particular, there is a cluster of 27 genes on chromosome 16. Children with autism may have only one copy of those genes, instead of the usual two. Scientists at Cold Spring Harbor Laboratory used mice that were genetically engineered to have this same kind of deletion defect. Then, they observed the mice.

"What we found was really, really amazing," says senior author Alea A. Mills. "They have a number of features that are used to diagnose children with autism. They're hyperactive, they have repetitive behaviors, and they have a lot of sleep deficits." Mills said they also studied the brains of the laboratory mice. Co-author Mark Henkleman, of the Hospital for Sick Children in Toronto, ran MRI scans on the mice.

"And what he found was that there were eight different regions of the brain that were severely affected. Interestingly, one of these regions of the brain is the hypothalamus," Mills says. And previous research has linked the hypothalamus with some repetitive behaviors that are characteristic of autism.

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So is this deletion – a missing second copy of this 27-gene cluster – the "cause" of autism? Mills says it's not that simple. "There are a number of different genetic changes that have been found [to be] associated with autism. There could be a network of interacting players, but I don't think there will be a single region [of the genome] that is responsible for all cases of autism, from what we're seeing."

Still, putting together pieces of the genetic puzzle surrounding autism may help researchers understand the disorder better, and that might lead someday to new therapies. And the development of mice with autism-like behaviors may help scientists in the process. The research paper by Alea Mills and colleagues is published in the Proceedings of the National Academy of Sciences. (VOA/JC)