title: Early generalized overgrowth in autism spectrum disorder: prevalence rates, gender effects, and clinical outcomes.
abstract: OBJECTIVE
  Although early head and body overgrowth have been well documented in autism spectrum disorder (ASD), their prevalence and significance remain unclear. It is also unclear whether overgrowth affects males and females differentially, and whether it is associated with clinical outcomes later in life.
  
  
  METHODS
  To evaluate prevalence of somatic overgrowth, gender effects, and associations with clinical outcomes, head circumference, height, and weight measurements were collected retrospectively between birth and 2 years of age in toddlers with ASD (n = 200) and typically developing (TD; n = 147) community controls. Symptom severity, verbal, and nonverbal functioning were assessed at 4 years.
  
  
  RESULTS
  Abnormalities in somatic growth in infants with ASD were consistent with early generalized overgrowth (EGO). Boys but not girls with ASD were larger and exhibited an increased rate of extreme EGO compared to community controls (18.0% versus 3.4%). Presence of a larger body at birth and postnatal overgrowth were associated independently with poorer social, verbal, and nonverbal skills at 4 years.
  
  
  CONCLUSIONS
  Although early growth abnormalities in ASD are less common than previously thought, their presence is predictive of lower social, verbal, and nonverbal skills at 4 years, suggesting that they may constitute a biomarker for identifying toddlers with ASD at risk for less-optimal outcomes. The results highlight that the search for mechanisms underlying atypical brain development in ASD should consider factors responsible for both neural and nonneural tissue development during prenatal and early postnatal periods, and can be informed by the finding that early overgrowth may be more readily observed in males than in females with ASD.
authors.affiliation: Amgen Inc., Thousand Oaks, CA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Campbell
authors.affiliation: Yale University, New Haven.
authors.forename: Joseph
authors.initials: J
authors.lastname: Chang
authors.affiliation: Child Study Center, Yale University School of Medicine, New Haven, CT. Electronic address: Katarzyna.Chawarska@yale.edu.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Chawarska
mesh_terms: D000067877:Autism Spectrum Disorder / Q000175:diagnosis*; D015415:Biomarkers; D002675:Child, Preschool; D005260:Female; D006257:Head / Q000254:growth & development*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015995:Prevalence; D012737:Sex Factors; D060726:Torso / Q000254:growth & development*
chemical_list: D015415:Biomarkers
keywords: autism; gender; head circumference; infancy; overgrowth