Abstract

Autism Spectrum Disorder (ASD) has increasingly become an important topic of research due to its status as a major public health concern. It exerts immense suffering on children and families and imposes an economic burden on society. As suggested by its name, ASD does not manifest in one form or present only a single set of symptoms, but instead contains heterogeneous sets of symptoms, leading to obstacles that obstruct the path to ASD etiology discovery. Under the DSM-5, a diagnosis of ASD requires deficits in social skills, communication, and repetitive behaviors (McPartland, Reichow, & Volkmar, 2012). Traditionally, researchers have focused on identifying genes that underlie most cases of ASD and have discovered several genes that correspond to a wide range of ASD cases. This approach, however, has limitations as ASD is now understood to have a much more complex set of causes than the known set of genes. In light of evidences suggesting the complexity of ASD etiology, some researchers have shifted focus from finding a universal cause for all symptoms of ASD to systematically grouping symptoms and comorbidities, and performing genetics studies to discover a set of genetic factors contributing to these groups of symptoms. Other researchers tackle the genotypic heterogeneity by attempting to identify genetic factors underlying phenotypically homogenous subgroups of ASD. Moreover, some researchers have broadened the scope of ASD etiology investigation to include the investigation of comorbidity etiology. This review elucidates the current strategies in discovering the biological basis of ASD research and highlights some of the most recent advancements in the understanding of ASD etiology.