Background: 16p11.2 Deletion (16p11.2del), one of the most common genomic copy number changes, results from the deletion of the recurrent ~600kb BP4-BP5 chromosomal region. It is associated with numerous neurodevelopmental outcomes including difficulties in cognition, language, motor coordination and psychiatric areas (Hanson et al., 2010, Hanson et al., 2015) and may account for up to .06% of all Autism Spectrum Disorder (ASD) cases (Bijlsma et al, 2009). 16p11.2del also shows increased rates of the broader ASD phenotype (difficulties in social, communication and stereotyped and repetitive behaviors (RRB’s)) without meeting full criteria for diagnosis (Hanson et al., 2015). Individually, these symptoms can still cause significant impairment. There has not yet been a study evaluating whether symptoms of the broader ASD phenotype in 16p11.2del are higher than in typically developing (TD) individuals.
The Social Responsiveness Scale (SRS; Constantino et al, 2005) is a parent questionnaire that measures symptoms associated with ASD using five subscales: Social Awareness (S-AWR), Social Cognition (S-COG), Social Communication (S-COM), Social Motivation (S-MOT), and RRB’s. The purpose of this study is to compare SRS scores of TD and 16p11.2del without ASD.
Methods: Preliminary analyses were run using previously collected data from 18 participants, 9 individuals with 16p11.2del from the Simons Variation in Individuals Project and 9 TD individuals from Simons Simplex Collection or Boston Autism Consortium, matched on Verbal IQ (VIQ).
Inclusion criteria included completed cognitive and SRS assessment and no ASD diagnosis. A T-test was used to compare SRS subscale means.
Results: Mean VIQ for 16p11.2del was 82 (SD=26) and for TD was 97 (SD=9). Significant differences were found between the two groups on the following subscales: S-AWR (p<0.01) S-COG (p=0.02) S-COM (p<0.01) RRBs (p=0.01) and Total SRS T-Scores (p=0.01). There was no significant difference for S-MOT (p=0.08).
Conclusion: 16p11.2del had significantly more difficulty across a number of symptom measures compared to TD. This confirms previous research that social impairment is present in this population and could significantly impact functioning. Future analyses will include larger numbers of participants in order to be able to look at specific differences in profiles including number, type and degree of symptoms. Evaluating profiles will help families and clinicians understand the strengths and difficulties in 16p11.2del population and design appropriate support services.