Infant head growth in male siblings of children with and without autism spectrum disorders

Departments of Psychiatry and Pediatrics, Washington University, Saint. Louis, Missouri.
Journal of Neurodevelopmental Disorders (Impact Factor: 3.45). 03/2010; 2(1):39-46. DOI: 10.1007/s11689-009-9036-5
Source: PubMed

ABSTRACT PURPOSE: Previous research has indicated that children with autism exhibit accelerated head growth (HG) in infancy, although the timing of acceleration varies between studies. We examined infant HG trajectory as a candidate autism endophenotype by studying sibling pairs. METHODS: We retrospectively obtained serial head orbitofrontal circumference measurements of: a) 48 sibling pairs in which one (n=28) or both (n=20) sibs were affected by an autism spectrum disorder (ASD); and b) 85 control male sibling pairs. RESULTS: Rate of HG of ASD subjects was slightly accelerated compared to controls, but the magnitude of difference was below the limit of reliability of standard measurement methods. Sibling intra class correlation for rate of HG was highly statistically significant; the magnitude was significantly stronger among autism-affected families (ICC=.63) than among controls (ICC=.26), p<.01. CONCLUSION: Infant HG trajectory appears familial-possibly endophenotypic-but was not a reliable marker of autism risk among siblings of ASD probands in this sample.

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    ABSTRACT: Objective While early brain overgrowth is frequently reported in autism spectrum disorder (ASD), the relationship between ASD and head circumference (HC) is less clear, with inconsistent findings from longitudinal studies that include community controls. Our aim was to examine whether head growth in the first 3 years differed between children with ASD from a high-risk (HR) sample of infant siblings of children with ASD (by definition, multiplex), HR siblings not diagnosed with ASD, and low-risk (LR) controls. Method Participants included 442 HR and 253 LR infants from 12 sites of the international Baby Siblings Research Consortium. Longitudinal HC data were obtained prospectively, supplemented by growth records. Random effects non-linear growth models were used to compare HC in HR infants and LR infants. Additional comparisons were conducted with the HR group stratified by diagnostic status at age 3: ASD (n=77), developmental delay (DD; n=32), and typical development (TD; n=333). Nonlinear growth models were also developed for height to assess general overgrowth associated with ASD. Results There was no overall difference in head circumference growth over the first 3 years between HR and LR infants, although secondary analyses suggested possible increased total growth in HR infants, reflected by the model asymptote. Analyses stratifying the HR group by 3-year outcomes did not detect differences in head growth or height between HR infants who developed ASD and those who did not, nor between infants with ASD and LR controls. Conclusion Head growth was uninformative as an ASD risk marker within this HR cohort.
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