Autism begins in the womb: study

Autism begins in the womb, according to a new study.

Scientists at the University of California, San Diego School of Medicine and the Allen Institute for Brain Science cite evidence of undeveloped cells as the explanation for the origin of autism.

By looking at 25 genes in postmortem brain tissue of children with and without autism, researchers realized autistic kids missed key genetic markers, or biomarkers, for brain cells that are supposed to develop prior to birth. The defects were found in regions that control emotion, communication, language and social comprehension -- all functions impaired in autism.

"Building a baby's brain during pregnancy involves creating a cortex that contains six layers," Dr. Eric Courchesne, professor of neurosciences and director of the Autism Center of Excellence at UC San Diego, said in a statement. "We discovered focal patches of disrupted development of these cortical layers in the majority of children with autism."

About one in 68 U.S. children may have autism, U.S. health officials said Thursday in a related report, according to Reuters.

While it's not clear what causes these brain cell abnormalities, the study, published in New England Journal of Medicine, brings researchers closer to early diagnosis and treatment, according to the authors.

Researchers examined brain samples from 22 deceased children, ages 2 to 15, half of whom were autistic. They found disorganized patches of defective cells in brain tissue from 10 of the 11 children with autism, compared to one of the 11 unaffected children, Bloomberg reported. Furthermore, they concluded that the disruption of cell development probably occurred in the second and third trimesters.

"We found a novel aspect of cortical development never seen before that provides clues to the potential cause of autism and when it began," Courchesne said. "The type of defect we found points directly and clearly to autism beginning during pregnancy."