Biomarker for autism may be on horizon TAMPA, Fla., Jan. 4 (UPI) -- Elevated levels of a protein fragment circulating in the blood may serve as a biomarker for autism, U.S. researchers say. Dr. Jun Tan of the University of South Florida's Silver Child Development Center said immune system abnormalities that mimic those seen with autism spectrum disorders have been linked to the amyloid precursor protein. The elevated levels of this protein fragment circulating in the blood could explain immune cell population changes observed in some autism patients, explained Tan, the study team leader. The findings, published online in the Journal of the Federation of American Societies for Experimental Biology, suggest the protein fragment might be both a biomarker for autism and a new research target for understanding the physiology of the disorder. "Autism affects one in 110 children in the United States today," Tan said in a statement. While there are reports of abnormal T-cell numbers and function in some persons affected with autism, no specific cause has been identified. The disorder is diagnosed by behavioral observation and to date no associated biomarkers have been identified. The amyloid precursor protein is typically the focus of research related to Alzheimer's disease, but researchers identified elevated levels of the particular protein fragment -- sAPP-α -- in the blood of autistic children. The fragment is a well-known growth factor for nerves, and studies imply that it plays a role in T-cell immune responses as well, Tan said.