Scientists from the UC Davis M.I.N.D. Institute recently presented new evidence that one day could lead to a diagnostic test for autism in infancy.

The researchers found that components of the immune system and proteins and metabolites in the blood of autistic children differ substantially from those found in the blood of children who did not have the disorder.

Investigators at the Institute believe the discovery, announced May 5 at the 4th International Meeting for Autism Research in Boston, could be a major step toward developing a routine blood test that would allow autism to be detected in newborns and allow treatment or even prevention to be initiated early in life.

"This is an important pilot experiment, a proof of principle," said David Amaral, research director at the M.I.N.D. Institute and one of the co-authors of the paper presented at the conference.

He added, "From these results, we think it is highly likely that there are differences we can detect in blood samples that will be predictive of the disorder, though we are still some years away from having an actual autism diagnostic blood test. Scientists have long suspected there were distinct biological components to autism but the technology needed to reveal them has only recently become available."

Over the last two decades parents, educators, scientists and pediatricians have been alarmed by a dramatic and baffling rise in the prevalence of autism, which now affects as many as one in every 166 children. But diagnosing autism, a brain disorder that leaves children in apparent isolation from their families and communities, is currently accomplished through a series of behavioral observations that are not reliable until a child is between 2- and 3-years-old.

"Finding a sensitive and accurate biological marker for autism that can be revealed by a simple blood test would have enormous implications for diagnosing, treating and understanding more about the underlying causes of autism," he said.

"Not being able to detect autism until a child is close to 3-years-old eliminates a valuable window of treatment opportunity during the first few years of life when the brain is undergoing tremendous development," Amaral pointed out.

Amaral, along with pediatric neuropsychologist Blythe Corbett and other M.I.N.D. Institute colleagues, took blood samples from 70 children with autism who were between 4 and 6 years old and from 35 children of the same age who did not have the disorder. The samples were then analyzed by a biotech company, SurroMed, LLC, Menlo Park, Calif., which has developed technology that can identify differences in the number and types of immune cells, proteins, peptides and metabolites in small amounts of blood.

Immune system differences

The study has generated an enormous amount of data and M.I.N.D. Institute researchers say it will take months before all of the information has been fully evaluated. But initial findings clearly demonstrate differences in the immune system, as well as proteins and other metabolites in children with autism:

• The antibody producing B cells are increased by 20 percent in the autism group;
• Natural killer cells are increased by 40 percent;
• More than 100 proteins demonstrated significant differential expression between the autism and typically developing groups;
• Other small molecules (metabolites) also show many differences.

Early tests important

Future research studies need to be done to confirm the findings in a larger group and with younger children. For example, researchers might take blood samples from newborns and then see if the results predicting autism are later confirmed by a behavioral diagnosis. Other studies would also use bioinformatics approaches to narrow down the number of proteins or metabolites that would need to be assayed to show the strongest link to autism.

"Discovering an early diagnostic test is an important focus of research," said Amaral. "There is a growing view among experts that not all children with autism are 'doomed to autism' at birth."

He said it may be that some children have a vulnerability — such as a genetic abnormality — and that something they encounter after being born, perhaps in their environment, triggers the disorder.

"Studying the biological signs of autism," Amaral noted, "could lead to new ways to prevent the disorder from ever occurring. And even if it can't be prevented, intervening early in life — ideally shortly after birth — could greatly improve the lifetime outlook for children with autism, particularly those who now respond poorly to therapy initiated when they are 3 or older."

Karen Finney and Carole Gan serve in the public affairs unit for the UC Davis Health System.