Abstract
Fragile X syndrome (FXS) is the leading known genetic cause of autism spectrum disorder (ASD) with 60–74% of males with FXS meeting diagnostic criteria for ASD. Infants with FXS have demonstrated atypical neural responses during face processing that are unique from both typically developing, low-risk infants and infants at high familial risk for ASD (i.e., infants siblings of children with ASD). In the current study, event-related potential (ERP) responses during face processing measured at 12 months of age were examined in relation to ASD symptoms measured at ~48 months of age in participants with FXS, as well as siblings of children with ASD and low-risk control participants. Results revealed that greater amplitude N290 responses in infancy were associated with more severe ASD symptoms in childhood in FXS and in siblings of children with ASD. This pattern of results was not observed for low-risk control participants. Reduced Nc amplitude was associated with more severe ASD symptoms in participants with FXS but was not observed in the other groups. This is the first study to examine ASD symptoms in childhood in relation to infant ERP responses in FXS. Results indicate that infant ERP responses may be predictive of later symptoms of ASD in FXS and the presence of both common and unique pathways to ASD in etiologically-distinct high-risk groups is supported (i.e., syndromic risk vs. familial risk).
Highlights
Fragile X syndrome (FXS) is a single-gene disorder that results from a CGG repeat expansion mutation on the X chromosome affecting approximately one in 3,700–8,900 males [1,2,3,4] and one in 11,100 females [4]
We investigated the possibility that neural responses to social and non-social stimuli in infancy, measured through event-related potential (ERP), may be associated with later-emerging symptoms of autism spectrum disorder (ASD) in infants with FXS contrasted against etiologically-distinct high-risk infants (ASIBs) and low-risk infants
The opposite pattern of responses was seen for low-risk control (LRC) infants, decreased N290 amplitude in response to faces was related to higher Overall calibrated severity scores (CSS), F(1, 214) = 20.81, p < 0.001, n2p = 0.09, 95% CI [0.03, 0.17]
Summary
Fragile X syndrome (FXS) is a single-gene disorder that results from a CGG repeat expansion mutation on the X chromosome affecting approximately one in 3,700–8,900 males [1,2,3,4] and one in 11,100 females [4]. FXS possesses a high level of comorbidity with autism spectrum disorder (ASD) and is the most common single-gene cause of ASD, evidenced by 60–74% of individuals with FXS meeting diagnostic criteria for ASD [5,6,7,8,9]. This is much higher than the rate of 1.9%, which is observed in the general population [10]. Specific neural responses [i.e., event-related potentials (ERPs)] related to ASD are atypical in infants with FXS at 12 months of age [13].
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