A Unique Visual Attention Profile Associated With the FMR1 Premutation

Abstract

Atypical visual attention patterns have been observed among carriers of the fragile X mental retardation gene (FMR1) premutation (PM), with some similarities to visual attention patterns observed in autism spectrum disorder (ASD) and among clinically unaffected relatives of individuals with ASD. Patterns of visual attention could constitute biomarkers that can help to inform the neurocognitive profile of the PM, and that potentially span diagnostic boundaries. This study examined patterns of eye movement across an array of fixation measurements from three distinct eye-tracking tasks in order to investigate potentially overlapping profiles of visual attention among PM carriers, ASD parents, and parent controls. Logistic regression analyses were conducted to examine whether variables constituting a PM-specific looking profile were able to effectively predict group membership. Participants included 65PM female carriers, 188 ASD parents, and 84 parent controls. Analyses of fixations across the eye-tracking tasks, and their corresponding areas of interest, revealed a distinct visual attention pattern in carriers of the FMR1 PM, characterized by increased fixations on the mouth when viewing faces, more intense focus on bodies in socially complex scenes, and decreased fixations on salient characters and faces while narrating a wordless picture book. This set of variables was able to successfully differentiate individuals with the PM from controls (Sensitivity = 0.76, Specificity = 0.85, Accuracy = 0.77) as well as from ASD parents (Sensitivity = 0.70, Specificity = 0.80, Accuracy = 0.72), but did not show a strong distinction between ASD parents and controls (Accuracy = 0.62), indicating that this set of variables comprises a profile that is unique to PM carriers. Regarding predictive power, fixations toward the mouth when viewing faces was able to differentiate PM carriers from both ASD parents and controls, whereas fixations toward other social stimuli did not differentiate PM carriers from ASD parents, highlighting some overlap in visual attention patterns that could point toward shared neurobiological mechanisms. Results demonstrate a profile of visual attention that appears strongly associated with the FMR1 PM in women, and may constitute a meaningful biomarker.

Keywords: autism spectrum disorder; eye tracking; fragile X mental retardation gene; fragile X syndrome; pragmatic language; social cognition.

Figure 1

ROC curves assessing discriminability across groups for the final logistic regression models on the averaged datasets.

Figure 2

Correlation matrix for genetics associations observed in the autism spectrum disorder (ASD) parent group across key areas of interest (AOI; ^*p < 0.05, ^**p < 0.01).

Figure 3

Comparisons of clinical-behavioral and FMR1-related variables between the premutation (PM) carriers who were misclassified as ASD parents and those who were correctly classified (^*p < 0.05, ^{^}p < 0.10). Of note, controls are not included in comparisons related to broad autism phenotype (BAP) features, and ASD parents and controls were not included in comparisons related to FMR1 molecular-genetic variation.

Figure 4

Comparison of ASD symptom severity as measured by the ADOS-2 in the children of PM carriers who were misclassified as ASD parents and those who were correctly classified (^{^}p < 0.10). The cut-off for meeting criteria for ASD is seven (range: 1–10).