Evidence of a distinct behavioral phenotype in young boys with fragile X syndrome and autism.

  • JJ W
  • JW B
  • HC H
 et al. 
  • 1


    Mendeley users who have this article in their library.
  • N/A


    Citations of this article.


Objective: How does the behavioral expression of autism in fragile X syndrome (FXS + Aut) compare with idiopathic autism (iAut)? Although social impairments and restricted, repetitive behaviors are common to these variants of autism, closer examination of these symptom domains may reveal meaningful similarities and differences. To this end, the specific behaviors comprising the social and repetitive behavioral domains in young children with FXS + Aut and iAut were profiled.Method: Twenty-three male subjects 3 to 5 years old with FXS + Aut were matched by age to a group of 38 boys with iAut. Repetitive behavior was assessed using the Repetitive Behavior Scales-Revised. Social behavior was evaluated using Autism Diagnostic Observation Schedule social item severity scores.Results: Rates of stereotypy, self-injury, and sameness behaviors did not differ between groups, whereas compulsive and ritual behavior scores were significantly lower for subjects with FXS + Aut compared with those with iAut. Those with FXS + Aut scored significantly lower (less severe) than the iAut group on five Autism Diagnostic Observation Schedule measurements of social behavior: gaze integration, quality of social overtures, social smile, facial expressions, and response to joint attention.Conclusions: The behavioral phenotype of FXS + Aut and iAut are most similar with respect to lower-order (motoric) restricted, repetitive behaviors and social approach, but differ in more complex forms of restricted, repetitive behaviors and some social response behaviors. These findings highlight the phenotypic heterogeneity of autism overall and its unique presentation in an etiologically distinct condition.

Author-supplied keywords

  • Autistic Disorder
  • Autistic Disorder -- Diagnosis
  • Autistic Disorder -- Psychosocial Factors
  • Behavior
  • Behavioral Symptoms
  • Behavioral Symptoms -- Diagnosis
  • Behavioral Symptoms -- Psychosocial Factors
  • Child Behavior
  • Child, Preschool
  • DSM
  • Diagnosis, Differential
  • Facial Expression
  • Fragile X Syndrome
  • Fragile X Syndrome -- Diagnosis
  • Fragile X Syndrome -- Psychosocial Factors
  • Human
  • Male
  • Multivariate Analysis
  • Nerve Tissue Proteins
  • Phenotype
  • Psychological Tests
  • Psychopathology
  • Social Behavior

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Wolff JJ

  • Bodfish JW

  • Hazlett HC

  • Lightbody AA

  • Reiss AL

  • J Piven

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free