17539
Examining the Overlap of Autism Spectrum Disorder and 22Q11 Deletion Syndrome Using Standardized Clinical Assessments
In order to better understand the biological causes of autism spectrum disorder (ASD), researchers have attempted to identify known genetic syndromes that may overlap with ASD. While some studies find that ASD does not co-occur with 22q11 deletion syndrome (22q11DS), others have found that between 15 and 50 percent of individuals with 22q11DS also have ASD.
Objectives:
Our study aimed to provide a conservative estimate of the occurrence of ASD among a cohort of children (ages 6-12) and adolescents/adults (ages 14-29) with 22q11DS, using rigorous, research-based diagnostic procedures.
Methods:
This study evaluated 56 participants between the ages of 6 to 29 with 22q11DS for ASD. We divided the total group into two cohorts, children (n = 23) ages 6 to 12 (M = 9.64, 48% female) and adults (n = 33) ages 14 to 29 (M = 19.60, 56% female). The Autism Diagnostic Interview-Revised (ADI-R) and Autism Diagnostic Observation Schedule (ADOS) were administered and, along with clinician best estimate diagnosis, informed ASD designation. Following the Collaborative Programs of Excellence in Autism (CPEA), we identified individuals as having autism, Asperger’s disorder, or pervasive developmental disorder – not otherwise specified (PDD-NOS) using a hierarchical algorithm.
Results:
Based on the ADOS, 41.1% of the participants’ scores met the cutoff for an ASD. When using the ADI-R, 37.5% met the cutoff for an ASD. We found that of our 56 participants, 10 (17.9%) met both the ADI-R and ADOS, and also received clinician’s best estimate of diagnosis as ASD; that is, they met CPEA criteria for an ASD. More than a third of participants (39.3%, n = 22) met neither the ADI-R nor ADOS cut-offs. In addition, ASD-related problems were evident in those who did not meet overall ASD diagnostic thresholds. In particular, 37.5% met the ADI-R cutoff for the social domain, 32.1% for the communication domain, and 46.4% for the repetitive behavior domain. ADI-R results indicate that more than half of our participants (66.1%, n = 37) met at least one of the social, communication, or repetitive behavior domain cut-offs (ADI-R sub domains A-C).
Conclusions:
The data support the conclusion that strictly defined ASDs do occur within the 22q11DS population. Knowledge of this association should lead to 1) earlier diagnosis of ASDs in individuals with 22q11DS and 2) targeted interventions and therapies, such as pharmacological and behavioral approaches (Vorstman, 2006). Awareness of this association may also lead to specific hypotheses regarding the etiology of ASD (Karam et al., 2010; Grayton et al., 2012). Thus, we recommend that all individuals with 22q11DS be screened for ASD as a part of their standard clinical care. Results will be discussed in regards to DSM 5 diagnoses of autism spectrum disorder and social (pragmatic) communication disorder.