As much as 23 percent of autism cases may be linked to antibodies in some mothers that attack proteins that are critical to fetal brain development, according to a landmark UC Davis study.
Scientists at the UC Davis MIND Institute have identified specific antibodies linked to "maternal autoantibody-related" (MAR) autism, according to a study published this week in a scientific journal.
The findings could lead to development of a diagnostic test to tell a woman considering pregnancy whether she has antibodies associated with MAR autism. In the long run, the research could lead to the development of drugs to block the antibodies during pregnancy.
The study is the first to identify a specific risk factor in a notable subset of autism cases, researchers said.
"These findings are incredibly important, because they establish a cause for a significant portion of autism cases, thereby opening up new lines of inquiry into possible biological treatments," MIND Institute Director Leonard Abbeduto said Tuesday in a written statement.
The study found that mothers of children with autism were more than 21 times more likely to have the specific MAR autism antibodies than mothers of children who did not have autism. The antibodies bind to proteins in the fetus that are involved in neuron development and "interfere with their function," said the study's principal investigator, Judy Van de Water of the MIND Institute.
Maternal antibodies, which cross through the placenta to protect the developing fetus, can be detected within 13 weeks. Once in the fetal bloodstream, however, the antibodies can enter the brain and target cells that have corresponding proteins that act as antigens. When they act against the body's own tissue – instead of against bacteria and viruses – the antibodies are called autoantibodies.
In the current study, investigators identified seven specific fetal proteins that react to the maternal antibodies. Researchers used blood samples from 246 mothers of children with autism and a control group of 149 mothers of children without autism.
The study found that mothers with antibodies that reacted to any of the proteins were more than three times as likely to have a child with an autism spectrum disorder.
"It is important to note that women have no control over whether or not they develop these autoantibodies, much like any other autoimmune disorder," Van de Water said. "And, like other autoimmune disorders, we do not know what the initial trigger is that leads to their production."
The findings by Van de Water's group were published online Tuesday in Translational Psychiatry.
The scientific journal also published a separate but related MIND Institute study involving monkeys. Researchers found that pregnant female monkeys exposed to human maternal antibodies linked to autism gave birth to offspring with abnormalities in social behavior and brain growth.
"When we see this in an animal model, it's very exciting because it parallels features of human autism," said Melissa Bauman, the study's co-principal investigator.
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