Variants in the Social-Emotional Phenotype of Children with Autism and Children with Fragile X Syndrome

Background: Autism spectrum disorders (ASD) and Fragile X Syndrome (FXS) have elements of shared neurobiology. Individuals living with either condition suffer from severe language and social impairments.  These impairments often manifest in distinctly different ways and may arise from different underlying origins. 

Objectives: This study aimed to identify similarities and differences in the ways children with ASD and FXS encode, interpret, and reason about social and emotional information.  Our central objective was to compare social-emotional learning (SEL) skill in children with ASD and children with FXS and to determine diagnosis-specificity of patterns of deficits.

Methods: SEL skill is a constellation of cognitive, affective, and regulatory processes that govern social behavior.  We compared the SEL phenotype of children with ASD to girls with FXS.  Autism diagnoses and severity were confirmed via the Social Communication Questionnaire and the Autism Diagnostic Observation Schedule.  Six children (ages 7-12 years) with autism (5 males, 1 female) were individually age-matched and compared to six full-mutation girls with FXS.  Three of the children with FXS also met criteria for autism spectrum disorders. 

We administered an assessment battery that measured the child’s:  (1) ability to label the emotion of faces and voices, (2) pragmatic language skills, (3) perspective-taking and theory of mind abilities, and (4) social problem-solving skills.

Results: Results indicate that, with the exception of performances on a measure of pragmatic language and one aspect of social problem solving, children with ASD tend to perform at a higher level than children with children with FXS.  Although not reaching significance, children with ASD were more accurate at labeling emotion from nonverbal cues than girls with FXS.  Children with ASD also performed significantly better than girls with FXS on the perspective-taking assessment.  Finally, although children with ASD were consistently better at identifying social problems, the children with FXS were more likely to identify a competent solution at first prompting.  Exploratory regression analyses showed that although the differences were partially mediated by IQ, they were not shown to be mediated by autism severity.

Conclusions: Although a small sample, these data suggest that children with ASD differ from girls with FXS with respect to SEL skill.  These data further suggest that the social phenotype characterizing ASD is qualitatively different than that which characterizes FXS.  Importantly, this is one of the few studies documenting SEL deficits in girls with FXS.  A larger sample is needed to confirm and extend the findings of this preliminary study.  Once the nature of SEL deficits are defined in these populations, future work may address the neurobiology of these differences and the development of interventions specific to each child’s struggles.