Some mothers of children with autism appear to have immune system antibodies in their blood that attack brain proteins in their foetuses, a new study finds."Autism is 'a riddle wrapped in a mystery inside an enigma'," said autism expert Dr. Andrew Adesman, who was not involved in the new study. "This latest research takes us one step closer to clearing away some of this befuddlement and suggests why some children may develop autism."
"If maternal antibodies are indeed responsible for causing some cases of autism, then there is the possibility that a blood test could be done prenatally or even prior to getting pregnant to assess one's risk of having a child on the autism spectrum disorder," added Adesman, who is chief of developmental and behavioural paediatrics at Cohen Children's Medical Center of New York, in New Hyde Park.
The research might also provide targets for drug development, said the team of researchers from the University of California, Davis MIND Institute.
They named the form of autism linked to these antibodies Maternal Autoantibody-Related (MAR) autism, and they believe it could account for up to 23% of all cases.
In the study, the researchers analysed blood samples from 246 mothers of children with autism and from 149 mothers of children without autism. Compared to mothers of typical children, mothers of children with autism were more than 21 times as likely to have the MAR antibodies in their systems that reacted with foetal brain proteins (antigens).
Specific combinations of MAR antibodies were not found in the blood of mothers of children without autism, according to the study published online July 9 in the journal Translational Psychiatry.
Previous studies by the same researchers found that women with certain antibodies in their bloodstreams had an increased risk of having a child with autism. Their children also exhibited more severe language delays, irritability and self-injurious behaviours compared to children with autism whose mothers did not have the antibodies in their blood.
"Now we will be able to better determine the role of each protein in brain development," study principal investigator Judy Van de Water, an immunologist and professor of internal medicine, said in a UC Davis Health System news release. "We hope that, one day, we will be able to tell a mother more precisely what her antibody profile means for her child, then target interventions more effectively."
"It is important to note that women have no control over whether or not they develop these auto-antibodies, much like any other autoimmune disorder," Van de Water stressed. "And, like other autoimmune disorders, we do not know what the initial trigger is that leads to their production."
Identifying the proteins and pathways associated with MAR autism might help reveal the causes of autism and possibly lead to new therapies, such as administering "antibody blockers" to the mother during pregnancy to prevent damage to the developing fetal brain, Van de Water said.
This research is leading to the development of a test for MAR autism, which would be available to the mothers of young children who are showing signs of developmental delay. If the test were positive, the child could receive early behavioural intervention.
A MAR test might also assess a mother's risk of having a child with autism prior to conception. UC Davis holds the patent on a potential test, the news release notes.
Another expert said the new findings do hold promise.
"Since the original discovery of an auto-antibody marker in the blood of some women who have a child affected with autism, research has focused on how to use this finding for better diagnosis and intervention of ASD," noted Alycia Halladay, senior director of environmental and clinical sciences at the advocacy group Autism Speaks. "This new study is an important step in that process."
But for his part, Adesman stressed that many cases of autism occur outside of the process described in the study. "Since there is no history of auto-antibodies for a large majority of children with autism, a blood test for auto-antibodies blood test would not be able to prevent most cases (or causes) of autism," he said.
In related research involving monkeys, another team at the UC Davis MIND Institute also found that specific antibodies in a mothers' blood cause brain changes in offspring that cause behavior and development problems.
According to Halladay, "these findings further demonstrate that disruptions of normal immune system functioning in pregnancy can lead to a disruption of brain development and in some cases, a diagnosis of autism."
The U.S. National Institute of Neurological Disorders and Stroke has more about autism.