Predictors, Parental Views, and Concordance Across Diagnostic Sources of Autism in Male Youth with Fragile X Syndrome: Clinical Best Estimate and Community Diagnoses

Autistic Traits Associated with the Fragile X Premutation Allele: The Neurodevelopmental Profile

Although most individuals who carry the Fragile X premutation allele, defined as 55-200 CGG repeats on the X-linked FMR1 gene (Fragile X Messenger Ribonucleoprotein 1 gene), do not meet diagnostic criteria for autism spectrum disorder, there is a suggestion of increased behaviors associated with subtle autistic traits. More autism associated characteristics have been reported among adults than children. This may highlight a possible worsening developmental trajectory, variable findings due to research quality or differences in number of studies done in adults vs children, rather than true developmental changes. This review is designed to examine the neurodevelopmental profile associated with the premutation allele from a developmental perspective, focused on autistic traits.

Characterising the social interaction style of autism in young adult males with fragile X syndrome

BACKGROUND

The characterisation of autism in fragile X syndrome (FXS) has been a source of controversy due to the complexity of disentangling autism traits from common features of the FXS phenotype. Autism in FXS is significantly underdiagnosed in the community, which may be partly due to insufficient clinical description of the social interaction profile of autism within the FXS phenotype. In this study, we applied a classic framework for characterising social interaction styles in autism to a sample of young adult males with FXS and co-occurring autism to enhance understanding of how the social challenges associated with autism manifest within FXS.

METHODS

Participants were 41 males (M age = 18 years) with FXS and co-occurring autism. Interaction samples were coded for expression of predominately 'active' (characterised by a desire to make social approaches) or 'passive' (characterised by lack of initiation of social approach towards others) interaction profiles. Differences in the expression of phenotypic features of FXS, including anxiety, attention-deficit/hyperactivity disorder, cognitive, adaptive and language impairments and autism symptom severity, were examined across those with passive and active interaction styles.

RESULTS

Approximately half of the sample was classified as active and half as passive, demonstrating diversity in the social phenotype of autism associated with FXS. The two subtypes did not differ in autism severity, anxiety or attention-deficit/hyperactivity disorder symptoms or in cognitive, adaptive or language abilities.

CONCLUSIONS

This study enhances understanding of FXS-associated autism by documenting phenotypic variability in the social interaction profile in this group, with active and passive social interaction styles represented. The two social interaction styles were not associated with differential expression of common phenotypic features of FXS, suggesting similar support needs.