Autism and Related Traits
Some of the associated clinical features of AS (e.g. hand-flapping, stereotypic behaviors, deficits in expressive language), overlap with certain features of autism. Generally speaking, clinicians should exercise caution when examining symptoms of autism within AS, because some AS patients have been mistakenly identified as having autism in lieu of AS [1], and some patients who exhibit features of autism when they are younger, may no longer exhibit these features as their cognition and their language skills improve.
There are, however, some studies that specifically examine the frequency and magnitude of autistic traits in individuals with AS. While some researchers demonstrate a lack of autistic traits or very low incidence of autism in individuals with AS [2, 3], several other studies have demonstrated that a percentage of individuals with AS do also meet criteria for autism [4-6]. Individuals with AS and co-morbid autism are more likely to show decreased eye gaze, fewer social overtures, use fewer nonverbal gestures, use another person’s body as a “tool” to communicate “for” them, have decreased shared enjoyment in interactions, and fewer socially directed vocalizations [4, 6].
In considering the differences in findings and clinical opinions across these studies, it is important to note that differences in sample selection, including differences in autism symptom severity across molecular subtypes of AS play a major role. Specifically, recent studies demonstrate that it is primarily deletion positive individuals with AS that exhibit greater symptom severity associated with autism, and within the deletion positive group, primarily children with larger, Class 1 deletions [7] [8]. Most recent findings indicate that these differences in symptoms of autism between the deletion subgroups are not related to differences in cognition (i.e. children with greater symptom severity were not necessarily lower functioning).
To summarize, studies seem to indicate that severity of autism symptoms in AS only affects a small proportion of AS patients, is associated with deletion size, and with a more aloof/withdrawn behavioral phenotype. There are four genes (NIPA 1, NIPA 2, CYFIP1, & GCP5) missing in Class I and present in Class II deletions (refer to diagram in Genetic Mechanisms that Cause AS section), one or more of which may have a role in the development of socialization skills and symptoms related to autism. For the small percentage of patients with AS who do exhibit more features of co-morbid autism, specific therapies such as applied behavioral analysis are quite helpful.
Repetitive behaviors (e.g. using objects or toys inappropriately), sensory interests (licking/mouthing, sniffing objects), and stereotypic motor movements (rocking, hand-flapping) are common to all individuals with AS and do not differentiate between those individuals who also have co-morbid autism [4, 6, 9]. In fact, some individuals with AS do exhibit some compulsions, rituals (e.g. hoarding, hiding of food or objects, food fads), and repetitive interests/playing with unusual objects [10]. These behaviors are primarily noted in older, and/or higher functioning individuals with AS and do seem to overlap with behaviors associated with Prader-Willi Syndrome; but the degree to which these associated behaviors are prevalent across the different molecular subclasses of individuals with AS has not yet been investigated. Additionally, the degree to which these behaviors may be responsive to pharmacological treatment has also not been investigated in formal clinical trials.
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