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

Short-term and Long-term Stability of the Autism Diagnostic Observation Schedule (ADOS-2) Calibrated Comparison Scores (CCS) and Classification Scores in Youth with Down Syndrome or Fragile X Syndrome with Intellectual Disability

Autism diagnosis in individuals with fragile X syndrome (FXS) or Down syndrome (DS) with co-occurring intellectual disability is complex since clinicians often must consider other co-occurring behavioral features. Understanding how best to assess the features of autism in individuals with these conditions is crucial. In this study, we consider the short-term and long-term psychometric consistency of the Autism Diagnostic Observation Schedule-2 (ADOS-2) calibrated comparison scores (CCSs) and ASD classifications in individuals with FXS or DS. 76 individuals with DS (39 males; Mage = 15.27) and 90 individuals with FXS (71 males; Mage = 14.52 years) completed an assessment battery (ADOS-2, abbreviated IQ assessment and semi-structured language sample) at three timepoints (initial visit, short-term stability visit, long-term stability visit). All CCSs were found to have short-and long-term consistency for both groups, with lowest reliability scores for the repetitive behaviors (RRB) CCSs. Decreased reliability of RRB CCSs was found in the DS group than the FXS group. Variable short- and long-term ASD classifications were observed in both groups, with significantly higher variability in the DS group. Across groups, participants with variable classifications had lower ADOS-2 CCSs and higher language scores than those with stable ASD classifications. In the FXS group, those with variable classifications earned higher cognitive scores than did participants with stable ASD classifications. These findings highlight the high incidence of autism symptomatology in individuals with DS or FXS and co-occurring intellectual disability, while elucidating the short- and long-term variability of symptom expression in the context of structured observational tasks such as the ADOS-2.

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.