The frequency of Autism Spectrum Disorders (ASDs) is increasing with a 30% reported increase in pediatric prevalence from 2012 to 2014 in the U.S. until present rates of about one in 68 children or 1.5% of children in the U.S. Yet, little is known about the etiology of this spectrum. As of now, ASD is diagnosed based on a series of behavioral tests and the DSM-V highlights behavioral characteristics that define ASD. The challenge for researchers is to try to uncover the biological basis for these typical behaviors in order to improve diagnosis and identify potential targets for treatment.

A multidisciplinary approach to understanding the biological basis for the behavioral symptoms is necessary in order to move forward. This includes analysis of the current animal models for ASD and their suitability, reviewing immunological, immunogenetic and epigenetic research, reassessing clinical diagnostic tools, and surveying radiological, pathological, and serological records for clues.

With over 500 animal models available with varying construct validity and face validity, and a variety of behavioral tests for animals (three chamber, T maze, elevated plus maze) and for humans (ADOS, ADIR, CARS, ABC) and still no FDA approved effective treatments for the core symptoms of autism, much more needs to be done to understand the behavioral features of autism and their underlying etiology.

Efforts at twin studies, identifying HLA associations, specific genes, single nucleotide variants (SNVs) or single nucleotide polymorphisms (SNPs), and hotspots for copy number variations (CNVs) in autism have yielded limited but promising results so far. In light of the fact that Rett Syndrome, Fragile X, and other genetic syndromes comorbid with ASD, have been shown to be associated with epigenetic modifications the theory that epigenetic mechanisms might potentially be associated with the etiology of ASD deserves more attention.

To date, radiological studies of autism have included magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), and proton magnetic resonance spectroscopy (1H MRS) studies. Findings including brain overgrowth, increased number of neurons and activation of microglia highlight the value of such studies in broadening our understanding of ASD.

Many serological studies aimed at identifying any abnormalities in the blood of children with ASD have yielded conflicting results. Nevertheless, various inflammatory cytokines and immunological markers reflecting immune dysfunction have been documented in ASD. Preliminary studies even suggest a correlation between certain antibodies and clinical severity. In order to counteract the heterogeneity of ASD, larger studies with broader screening of immune factors are necessary.

Annual expenses for children with ASD were more than seven times the expenses for typically developing (“TD”) children and the cost of lifelong care to the health care system is $3.2 million dollars for every ASD patient in the United States. The need for further research in the field is clear. In this volume, experts from a wide array of fields will present the most updated research on ASD in an attempt to combine efforts and uncover the biological basis for the characteristic behavior.

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.