Over 7 percent of these cases have been tied to chromosomal defects, suggesting that many of the impairments in social communication, movement, sensory perception, and behavior that characterize the syndrome are down to genes.
Specifically, some people with ASD are missing a piece of their chromosome 16.
Known as 16p11.2 deletion syndrome, this chromosomal defect often leads to neurodevelopmental disability and language skills impairment.
Now, researchers may have found a way to reverse this genetic form of ASD. Scientists led by Prof. Riccardo Brambilla — of Cardiff University in the United Kingdom — used experimental drugs that were initially developed to treat cancer to restore normal brain function in mice with ASD-like symptoms.
The findings are now published in The Journal of Neuroscience.
Cancer drug prevents, reverses ASD in mice
"The human 16p11.2 microdeletion," explain Prof. Brambilla and team, "is one of the most common gene copy number variations 56 linked to autism."
But, the mechanisms that link the chromosomal defect with the neurodevelopmental condition are poorly understood. So, the team designed a mouse model of this chromosomal deficit to examine its pathophysiology.
The mice that had the defect displayed a series of behavioral and molecular abnormalities. These included hyperactivity, dysfunctions in their maternal behavior, and problems with their olfactory perception.
Moreover, the researchers found that mice with 16p11.2 deletion also had higher levels of a protein called ERK2.
ERK2 has been recently emerging as a target in cancer therapy, explain the researchers. This prompted the scientists to test the effect of experimental cancer drugs on mice with 16p11.2 deletion.
The drugs stopped ERK2 from reaching the rodents' brains, which reversed the ASD-like behavioral, neurological, and sensory symptoms in the mice.
"Importantly," the authors write, "we show that treatment with a novel ERK pathway inhibitor during a critical period of brain development rescues the molecular, anatomical, and behavioral deficits in the 16p11.2 deletion mice."
"By limiting the function of the protein that appears to cause autism symptoms in people with the chromosome 16 defect," explains Prof. Brambilla, "the trial drug not only provided symptomatic relief when administered to adult mice, but also prevented genetically predisposed mice from being born with the form of ASD."
This occurred as a result of administering the experimental drugs to the mother during gestation. The researcher explains what this means for humans.
"While it wouldn't be feasible to treat pregnant women who have been screened for the genetic abnormality, it could be possible, in principle, to permanently reverse the disorder by treating a child as early as possible after birth."
Prof. Riccardo Brambilla
"In the case of adults with the condition, ongoing medication would probably be required to treat symptoms," he adds.
In the future, the scientists hope to replicate the findings and ultimately test the drugs in clinical trials for people with ASD.