Abstract
BackgroundPhelan McDermid syndrome (PMS) is a neurogenetic condition associated with a high prevalence of intellectual disability (ID) and autism spectrum disorder (ASD). This study provides a more comprehensive and quantitative profile of repetitive behaviors within the context of ID seen with the condition.MethodsIndividuals age 3–21 years with a confirmed PMS diagnosis participated in a multicenter observational study evaluating the phenotype and natural history of the disorder. We evaluated data collected from this study pertaining to repetitive behaviors from the Repetitive Behavior Scales-Revised (RBS-R).ResultsThere were n = 90 participants who were part of this analysis. Forty-seven percent (n = 42/90) were female, and the average age at baseline evaluation was 8.88 ± 4.72 years. The mean best estimate IQ of the cohort was 26.08 ± 17.67 (range = 3.4–88), with n = 8 with mild ID (or no ID), n = 20 with moderate ID, and n = 62 with severe-profound ID. The RBS-R total overall score was 16.46 ± 13.9 (compared to 33.14 ± 20.60 reported in previous studies of ASD) (Lam and Aman, 2007), and the total number of items endorsed was 10.40 ± 6.81 (range = 0–29). After statistical correction for multiple comparisons, IQ correlated with the RBS-R stereotypic behavior subscale score (rs = − 0.33, unadjusted p = 0.0014, adjusted p = 0.01) and RBS-R stereotypic behavior total number of endorsed items (rs = − 0.32, unadjusted p = 0.0019, adjusted p = 0.01). IQ did not correlate with any other RBS-R subscale scores.ConclusionsThe RBS-R total overall score in a PMS cohort appears milder compared to individuals with ASD characterized in previous studies. Stereotypic behavior in PMS may reflect cognitive functioning.
Highlights
Phelan McDermid syndrome (PMS) is a neurogenetic condition associated with a high prevalence of intellectual disability (ID) and autism spectrum disorder (ASD)
In one study that administered the Autism Diagnostic Interview-Revised (ADI-R) to a group that did not have mental ages established to determine validity of the measure, 90% of individuals with PMS had deficits in social-communication above the diagnostic cutoff established for this measure, while 55% were above the cutoff for restricted, repetitive patterns of behavior, interests, or activities [2]
Previous studies suggest a relationship between repetitive behaviors and IQ in ASD [10,11,12,13] and other conditions associated with ASD and ID, such as fragile X syndrome (FXS) [14], it will be valuable to determine if this relationship is maintained in individuals with severe to profound ID or if there is a unique profile of repetitive behaviors in PMS
Summary
Phelan McDermid syndrome (PMS) is a neurogenetic condition associated with a high prevalence of intellectual disability (ID) and autism spectrum disorder (ASD). In one study that administered the Autism Diagnostic Interview-Revised (ADI-R) to a group that did not have mental ages established to determine validity of the measure, 90% of individuals with PMS had deficits in social-communication above the diagnostic cutoff established for this measure, while 55% were above the cutoff for restricted, repetitive patterns of behavior, interests, or activities [2]. Previous studies suggest a relationship between repetitive behaviors and IQ in ASD [10,11,12,13] and other conditions associated with ASD and ID, such as fragile X syndrome (FXS) [14], it will be valuable to determine if this relationship is maintained in individuals with severe to profound ID or if there is a unique profile of repetitive behaviors in PMS
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