Biomarker An Important Step Toward Objective Diagnostic Test for Autism
Currently, there is not an objective medical test that can diagnose autism. Instead, trained physicians administer autism-specific behavioral evaluations. But with new diagnostic guidelines set to go into effect next year, this process could get harder and may change the number of individuals who qualify for being included within the spectrum of autism disorders. Scientists are working on finding biomarkers that are important to one day creating an objective medical test that will improve the accuracy of diagnosis.
Children are typically screened for autism sometime before their third birthday. Evaluations such as the Modified Checklist of Autism in Toddlers, or M-CHAT, are used in order to refer high-risk patients to a specialist such as a developmental pediatrician, neurologist, psychiatrist or psychologist. But because these questionnaires have such as subjective element to them, some kids are missed, delaying diagnosis and the opportunity for early intervention therapies.
Researchers at Uppsala University have captured promising biomarkers in blood samples using advanced mass spectrometry. In addition to the potential for developing a reliable blood-based diagnostic tool, biomarkers may also help pharmaceutical companies create medications that can help with some of the core symptoms of autistic children.
Many diseases are caused by protein alterations inside and outside the body’s cells. By studying these patterns in tissue and body fluids, these dysfunctional proteins or peptides can be mapped out to provide important information about the underlying causes of disease.
A biomarker found to be connected with autism spectrum disorders is the complement factor C3 protein. A complement is a complex system that is part of the immune system. The research team has identified peptides consisting of fragments of C3 in a small number of children. C3 functions to promote phagocytosis, support local inflammatory processes against pathogens and instructs the adaptive immune response to select appropriate antigens. However, when this protein is unregulated, it can lead to cell damage.
In autism, C3 fragments may disrupt the nervous system.
Recently the CDC announced that the incidence of autism is increasing and it is estimated that one in 88 children have the disorder. But what is unknown is whether more children are actually developing autism because of genetic or environmental causes, or if the diagnosis is increasing because of awareness.
The proposed changes in the guidelines for qualifying for an autism spectrum disorder (ie; the Fifth edition of the American Psychiatric Association's "Diagnostic and Statistical Manual of Mental Disorders”) may further confuse the issue. Having a medical diagnostic test is important for accurate diagnosis of children so each gets the most appropriate treatment.
N Momeni, J Bergquist, L Brudin, F Behnia, B Sivberg, M T Joghataei, B L Persson. A novel blood-based biomarker for detection of autism spectrum disorders.Translational Psychiatry, 2012; 2 (3): e91 DOI:10.1038/tp.2012.19
A Sahu, JD Lambris. Structure and biology of complement protein C3, a connecting link between innate and acquired immunity. Immunol Rev. 2001 Apr;180:35-48.
Journal of the American Academy of Child & Adolescent Psychiatry, Vol. 51, No. 4 (April 2012)