Abstract
BackgroundFragile X syndrome (FXS) is the leading inherited cause of autism spectrum disorder, but there remains debate regarding the clinical presentation of social deficits in FXS. The aim of this study was to compare individuals with FXS to typically developing controls (TDC) and individuals with idiopathic autism spectrum disorder (ASD) across two social eye tracking paradigms.MethodsIndividuals with FXS and age- and gender-matched TDC and individuals with idiopathic ASD completed emotional face and social preference eye tracking tasks to evaluate gaze aversion and social interest, respectively. Participants completed a battery of cognitive testing and caregiver-reported measures for neurobehavioral characterization.ResultsIndividuals with FXS exhibited reduced eye and increased mouth gaze to emotional faces compared to TDC. Gaze aversive findings were found to correlate with measures of anxiety, social communication deficits, and behavioral problems. In the social interest task, while individuals with idiopathic ASD showed significantly less social preference, individuals with FXS displayed social preference similar to TDC.ConclusionsThese findings suggest fragile X syndrome social deficits center on social anxiety without the prominent reduction in social interest associated with autism spectrum disorder. Specifically designed eye tracking techniques clarify the nature of social deficits in fragile X syndrome and may have applications to improve phenotyping and evaluate interventions targeting social functioning impairments.
Highlights
Fragile X syndrome (FXS) is the leading inherited cause of autism spectrum disorder, but there remains debate regarding the clinical presentation of social deficits in FXS
All participants were evaluated by a child psychiatrist who specializes in FXS and autism spectrum disorder (ASD) with inclusion of previous ADOS results when available
Social interest Statistically significant group differences were observed on the social scene preference ratio (SSPR) [F(2, 46) = 3.40, p = 0.042]
Summary
Fragile X syndrome (FXS) is the leading inherited cause of autism spectrum disorder, but there remains debate regarding the clinical presentation of social deficits in FXS. Fragile X syndrome (FXS) is the leading inherited cause of neurodevelopmental disability and is characterized by a CGG trinucleotide repeat expansion in the promoter region of the fragile X mental retardation 1 gene (FMR1) on the long arm of the X chromosome. Hypermethylation of the trinucleotide repeat expansion (≥ 200 CGG repeats is termed “full mutation” and causes FXS) leads to silencing of the FMR1 gene and marked reduction or loss of expression of the fragile X mental retardation protein (FMRP). Anxiety is one of the hallmarks of the FXS behavioral phenotype with reports of over 70% of males and 56– 77% of females reporting anxiety symptoms and meeting criteria for an anxiety disorder, predominantly social
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