Autism spectrum disorder in Prader-Willi syndrome: A systematic review.

Prader-Willi syndrome (PWS) is a rare genetic disorder that results from lack of expression of paternally-derived genes on chromosome 15q11-13; caused by a deletion (DEL), uniparental disomy (UPD), or a rare imprinting center defect. PWS is associated with a distinct behavioral phenotype that in some respects overlaps with autism spectrum disorder (ASD), a neurodevelopmental disorder characterized by restricted or repetitive behaviors (RRBs) and social-communication impairment. The goal of this review was to (i) review published literature investigating core ASD symptoms in PWS and (ii) provide a prevalence estimate of ASD in PWS. Two independent reviewers searched Medline, CINAHL, PsychINFO, Embase, and Web of Science to find studies that answered the research questions. Individuals with PWS demonstrate significant levels of RRBs and social-communication impairment, in some reports reaching similar levels to those of non-PWS ASD comparison groups. Individuals with UPD had more social-communication impairment than those with DEL. Of 786 PWS participants, 210 (26.7%) were reported as meeting criteria for ASD, either based on clinical diagnosis or by exceeding clinical cut-points on relevant ASD symptom measures. In studies that distinguished genetic subtypes, rates of ASD were higher in individuals with PWS with UPD (67 of 190; 35.3%) than those with DEL (47 of 254; 18.5%). Published data on the association of PWS and ASD to date are limited to sample means of 8 years of age and older. Further research is needed to identify early markers of ASD in PWS children, to support earlier diagnosis and intervention for this important comorbidity.