title: Beyond autism: a baby siblings research consortium study of high-risk children at three years of age.
abstract: OBJECTIVE
  First-degree relatives of persons with an autism spectrum disorder (ASD) are at increased risk for ASD-related characteristics. As little is known about the early expression of these characteristics, this study characterizes the non-ASD outcomes of 3-year-old high-risk (HR) siblings of children with ASD.
  
  
  METHODS
  Two groups of children without ASD participated: 507 HR siblings and 324 low-risk (LR) control subjects (no known relatives with ASD). Children were enrolled at a mean age of 8 months, and outcomes were assessed at 3 years. Outcome measures were Autism Diagnostic Observation Schedule (ADOS) calibrated severity scores, and Mullen Verbal and Non-Verbal Developmental Quotients (DQ).
  
  
  RESULTS
  At 3 years, HR siblings without an ASD outcome exhibited higher mean ADOS severity scores and lower verbal and non-verbal DQs than LR controls. HR siblings were over-represented (21% HR versus 7% LR) in latent classes characterized by elevated ADOS severity and/or low to low-average DQs. The remaining HR siblings without ASD outcomes (79%) belonged to classes in which they were not differentially represented with respect to LR siblings.
  
  
  CONCLUSIONS
  Having removed a previously identified 18.7% of HR siblings with ASD outcomes from all analyses, HR siblings nevertheless exhibited higher mean levels of ASD severity and lower levels of developmental functioning than LR children. However, the latent class membership of four-fifths of the HR siblings was not significantly different from that of LR control subjects. One-fifth of HR siblings belonged to classes characterized by higher ASD severity and/or lower levels of developmental functioning. This empirically derived characterization of an early-emerging pattern of difficulties in a minority of 3-year-old HR siblings suggests the importance of developmental surveillance and early intervention for these children.
authors: University of Miami, Coral Gables, FL 33124-0721, USA. dmessinger@miami.edu
authors: Daniel
authors: D
authors: Messinger
authors: Gregory S
authors: GS
authors: Young
authors: Sally
authors: S
authors: Ozonoff
authors: Karen
authors: K
authors: Dobkins
authors: Alice
authors: A
authors: Carter
authors: Lonnie
authors: L
authors: Zwaigenbaum
authors: Rebecca J
authors: RJ
authors: Landa
authors: Tony
authors: T
authors: Charman
authors: Wendy L
authors: WL
authors: Stone
authors: John N
authors: JN
authors: Constantino
authors: Ted
authors: T
authors: Hutman
authors: Leslie J
authors: LJ
authors: Carver
authors: Susan
authors: S
authors: Bryson
authors: Jana M
authors: JM
authors: Iverson
authors: Mark S
authors: MS
authors: Strauss
authors: Sally J
authors: SJ
authors: Rogers
authors: Marian
authors: M
authors: Sigman
mesh_terms: D002659:Child Development Disorders, Pervasive / Q000175:diagnosis* / Q000235:genetics; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007361:Intelligence Tests; D008297:Male; D010641:Phenotype; D011569:Psychiatric Status Rating Scales; D012306:Risk; D012720:Severity of Illness Index; D035781:Siblings / Q000523:psychology*