Genetic signatures point to disrupted neuro-immune pathwaysBOSTON, Dec. 5, 2012 /PRNewswire-USNewswire/ -- Researchers at Boston Children's Hospital have developed a blood test for autism spectrum disorders (ASDs) that outperforms existing genetic tests, while presenting evidence that abnormal immunologic activity affecting brain development may help explain some of autism's origins. The findings also suggest a new direction for genetic research on autism and the search for treatments. The blood test, described December 5 in the online open access journal PLOS ONE and based on the largest gene-chip investigation ever done in autism, could enable early diagnosis of autism in about two thirds of patients before clear symptoms start to appear (the average age of diagnosis in the U.S. is 5 years). Researchers led by Sek Won Kong, MD, of the Boston Children's Hospital Informatics Program (CHIP) analyzed blood samples from 66 male patients with ASDs (from Boston Children's and several other hospitals in collaboration with the Autism Consortium of Boston) and compared them with 33 age-matched boys without ASDs. Using microarrays, they looked for RNA signatures reflecting differences in gene activity, or expression, between the two groups. "Since brain biopsy isn't a viable option for research, we asked whether blood could serve as a proxy for gene expression in the brain," says Isaac Kohane, MD, PhD, director of CHIP and senior investigator on both studies. "We found that it could, though we and others were initially skeptical." Analyzing the blood samples, Kong and colleagues flagged 489 genes as having distinct expression patterns in the ASD group, then narrowed this to a group of 55 genes that correctly identified or ruled out autism in 76 percent of samples. They validated their findings in a second group of 104 male and female patients with ASDs and 82 controls, achieving an overall classification accuracy of 68 percent (73 percent for males and 64 percent for females).