Autism spectrum and obsessive-compulsive disorders: OC behaviors, phenotypes and genetics

Abstract

Autism spectrum disorders (ASDs) are a phenotypically and etiologically heterogeneous set of disorders that include obsessive-compulsive behaviors (OCB) that partially overlap with symptoms associated with obsessive-compulsive disorder (OCD). The OCB seen in ASD vary depending on the individual's mental and chronological age as well as the etiology of their ASD. Although progress has been made in the measurement of the OCB associated with ASD, more work is needed including the potential identification of heritable endophenotypes. Likewise, important progress toward the understanding of genetic influences in ASD has been made by greater refinement of relevant phenotypes using a broad range of study designs, including twin and family-genetic studies, parametric and nonparametric linkage analyses, as well as candidate gene studies and the study of rare genetic variants. These genetic analyses could lead to the refinement of the OCB phenotypes as larger samples are studied and specific associations are replicated. Like ASD, OCB are likely to prove to be multidimensional and polygenic. Some of the vulnerability genes may prove to be generalist genes influencing the phenotypic expression of both ASD and OCD while others will be specific to subcomponents of the ASD phenotype. In order to discover molecular and genetic mechanisms, collaborative approaches need to generate shared samples, resources, novel genomic technologies, as well as more refined phenotypes and innovative statistical approaches. There is a growing need to identify the range of molecular pathways involved in OCB related to ASD in order to develop novel treatment interventions.

Figure 1

Developmental and genetic variables and their interaction influence the emergence of obsessive–compulsive behaviors in individuals with Autism Spectrum Disorders. Both genes and events affecting the course of brain development can influence the emergence of autism spectrum disorders (ASD) and Obsessive–compulsive behaviors (OCB). Some genes may also influence an individual’s exposure to risk (and protective) environments. There is also a growing body of evidence on the importance of gene–environment interactions (G×E) in relation to ASD and obsessive–compulsive disorder such that even adverse experiences might have a negligible effect in the absence of relevant susceptibility genes and yet have a very large effect in the presence of such genes.