A disrupted cell layering process in the brain could be a sign of prenatal autism. 

"While autism is generally considered a developmental brain disorder, research has not identified a consistent or causative lesion," Thomas R. Insel, M.D., director of the National Institute of Mental Health said in a news release. "If this new report of disorganized architecture in the brains of some children with autism is replicated, we can presume this reflects a process occurring long before birth. This reinforces the importance of early identification and intervention."

In the past researchers have noticed patches of abnormal neurons in the brains of autistic children, but this is the first time researchers have spotted brain abnormalities before birth. 

Researchers Eric Courchesne, Ph.D. and Rich Stoner, Ph.D., of the Autism Center of Excellence at the University of California reported that they found "an overabundance of neurons in the prefrontal cortex of children with autism," the news release reported. 

Researchers analyzed brain tissue postmortem of children both with and without autism who were between the ages of two and 15. 

While the brain is developing neurons in the cortex separate into six layers, each containing cells with unique connection patterns. The researchers looked at genes that worked as cellular markers for the cortical layers as well as those associated with autism. 

In 91 percent of the autistic case samples the markers for a number of layers of the cortex were not present; this phenomenon occurred in only nine percent of non-autistic samples. These "signs of disorganization" were found in patches that were between five and seven millimeters long. These patches were mostly found on the frontal and temporal lobes of the cortex, which are known to regulate: " social, emotional, communication, and language functions," the news release reported. Disturbances in these types of functions are common characteristics of autism.