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. 2010 Sep;49(9):921-33.
doi: 10.1016/j.jaac.2010.07.001. Epub 2010 Aug 1.

Autism in fragile X syndrome: a category mistake?

Scott S Hall  1 , Amy A Lightbody, Melissa Hirt, Ava Rezvani, Allan L Reiss
Affiliations

Autism in fragile X syndrome: a category mistake?

Scott S Hall et al. J Am Acad Child Adolesc Psychiatry. 2010 Sep.

Abstract

Objective: Many investigators now routinely classify children with fragile X syndrome (FXS) according to whether or not they also meet diagnostic criteria for autism. To determine whether this classification is appropriate, we examined the profiles of autistic behaviors shown by boys and girls with FXS.

Method: Individuals with FXS, aged 5 to 25 years, were assessed on two established measures of autism, the Social Communication Questionnaire (SCQ) and the Autism Diagnostic Observation Schedule (ADOS).

Results: We found that 35.1% of boys and 4.3% of girls with FXS scored in the "autism" category on both instruments. Analysis of the symptom profile indicated that both boys and girls with FXS showed lower rates of impairment on communication and reciprocal social interaction items than the reference autism samples on the measures. Furthermore, a regression model showed that IQ was significantly negatively associated with the SCQ total score in both boys and girls with FXS, when controlling for age, medication use, and FMRP levels.

Conclusions: These data suggest that there are significant differences in the profile of social and communicative symptomatology in FXS compared with individuals diagnosed with idiopathic autism. Given these differences, the implementation of standard autism interventions for individuals with FXS may not be optimal. Maintaining the conceptual distinction between FXS (an established biological disease) and idiopathic autism (a phenomenologically defined behavioral disorder) may also facilitate the development of more targeted and thus effective interventions for individuals with FXS in the future.

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Figures

Figure 1
Figure 1
Social Communication Questionnaire (SCQ) Communication domain. Note: Odds ratios comparing the percentage of boys and girls with fragile X syndrome (FXS) on items in the communication domain of the SCQ to those given in the SCQ manual. A 99% confidence interval for each odds ratio is also shown.
Figure 2
Figure 2
Social Communication Questionnaire (SCQ) social interaction domain. Note: Odds ratios comparing the percentage of boys and girls with fragile X syndrome (FXS) on items in the social interaction domain of the SCQ to those given in the SCQ manual. A 99% confidence interval for each odds ratio is also shown.
Figure 3
Figure 3
Social Communication Questionnaire (SCQ) repetitive behavior domain. Note: Odds ratios comparing the percentage of boys and girls with fragile X syndrome (FXS) on items in the repetitive behavior domain of the SCQ to those given in the SCQ manual. A 99% confidence interval for each odds ratio is also shown.
Figure 4
Figure 4
Autism Diagnostic Observation Schedule (ADOS) communication domain. Note: Mean item scores obtained on the communication domain of the ADOS for boys and girls with fragile X syndrome (FXS) compared to the ADOS reference sample.
Figure 5
Figure 5
Autism Diagnostic Observation Schedule (ADOS) social interaction domain. Note: Mean item scores obtained on the social interaction domain of the ADOS for boys and girls with fragile X syndrome (FXS) compared to the ADOS reference sample.
See this image and copyright information in PMC

References

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