Early acceleration of head circumference in children with fragile x syndrome and autism.
OBJECTIVE
Head circumference (HC) growth has been shown in several studies to be accelerated early in life in both fragile X syndrome (FXS) and autism spectrum disorders (ASDs), but the rates of growth have not been compared between those with only FXS and those with FXS and ASD (FXS + ASD).


METHODS
We hypothesized that individuals with FXS + ASD would have significantly larger HCs from individuals with only FXS and that there would be an early acceleration of HC in both the FXS-only and FXS + ASD groups. HC measurements were available retrospectively for 44 males, five and younger, with FXS, of whom 22 also had ASD. Measurements over time were available for 24 of the 44 children. HC percentiles were compared between the groups in two ways: by focusing on cross-sectional subsamples and by fitting hierarchical linear models to the full sample.


RESULTS
Neither group differed significantly from the norm in the first year of life (p > 0.2). At 30 months, the FXS + ASD group was 27 percentile points above the norm (p = .0125), whereas the FXS-only group did not differ from the norm. At 60 months, the FXS-only group was 21 percentile points above the norm (p = .029), whereas the FXS + ASD group did not differ from the norm.


CONCLUSIONS
The group difference in HC growth rate may differentiate brain development in individuals with FXS-only versus those with FXS + ASD.
Chiu
Sufen
S
Department of Psychiatry and Behavioral Sciences and MIND Institute, University of California Davis, Davis, CA 95817, USA. sufen.chiu@ucdmc.ucdavis.edu
Wegelin
Jacob A
JA
Blank
Jeremy
J
Jenkins
Megan
M
Day
Josh
J
Hessl
David
D
Tassone
Flora
F
Hagerman
Randi
R
D000886:Anthropometry; D001321:Autistic Disorder / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D005600:Fragile X Syndrome / Q000453:epidemiology*; D006257:Head / Q000254:growth & development*; D006801:Humans; D008297:Male; D012189:Retrospective Studies