A new study claims to show for the first time that autism begins in the womb, while another examines possible environmental influences on autism development.
The origins of autism have been passionately debated by many scientists and commentators. What is known about autism is that it is a physical condition, which is linked to abnormal biology and brain chemistry.
Genes seem to play an important part in the development of autism – identical twins, for instance, are much more likely to both have autism than non-identical siblings. But there has not been any clear consensus in medical opinion about what other contributing causes there may be.
Some things that have been suspected as being linked to autism – but which have not been proven – include diet, changes in the digestive tract, mercury poisoning, problems with the body processing vitamins and minerals, and vaccines.
A recent, large study in the journal PLoS Computational Biology suggests that environmental pollution could be a contributing factor to autism risk, but the study was unable to name any specific toxins that might be responsible.
That study assessed 100 million US health insurance claims to look at rates of autism on a county-by-county basis. It also used genital malformations in boys – micropenis, undescended testicles and cases where the urethral opening is on the underside of the penis – as indicators of environmental pollution.
The researchers found that for every 1% increase in genital birth defects in a county, the rate of autism there increased by nearly 300%.
“Both genes and environment are important,” emphasizes the lead researcher, Andrey Rzhetsky, a professor of genetic medicine at the University of Chicago in Illinois.
Study finding an in-utero basis for autism is the first to do so
The other new study, published in the New England Journal of Medicine, analyzed the brain tissue of children with autism.
The researchers – from the University of California, San Diego School of Medicine and the Allen Institute for Brain Science in Seattle, WA – examined 25 genes in the postmortem brain tissue of children with and without autism. These genes included biomarkers for brain cells in different layers of the cortex, genes that have been linked to autism and several control genes.
Analyzing the brain tissue of deceased children who had autism breaks ground with previous research, which instead has used the brain tissue of adults with autism and attempted to extrapolate back to what might have occurred developmentally.
The team found that key genetic markers across multiple layers of brain cells were missing in the brains of autistic children.