title: Syntactic complexity during conversation of boys with fragile X syndrome and Down syndrome.
abstract: OBJECTIVE
  This study compared the syntax of boys who have fragile X syndrome (FXS) with and without autism spectrum disorder (ASD) with that of (a) boys who have Down syndrome (DS) and (b) typically developing (TD) boys.
  
  
  METHODS
  Thirty-five boys with FXS only, 36 boys with FXS with ASD, 31 boys with DS, and 46 TD boys participated. Conversational language samples were evaluated for utterance length and syntactic complexity (i.e., Index of Productive Syntax; H. S. Scarborough, 1990).
  
  
  RESULTS
  After controlling for nonverbal mental age and maternal education levels, the 2 FXS groups did not differ in utterance length or syntactic complexity. The FXS groups and the DS group produced shorter, less complex utterances overall and less complex noun phrases, verb phrases, and sentence structures than did the TD boys. The FXS with ASD group and the DS group, but not the FXS-only group, produced less complex questions/negations than did the TD group. Compared with the DS group, both FXS groups produced longer, more complex utterances overall, but on the specific complexity measures, they scored higher only on questions/negations.
  
  
  CONCLUSIONS
  Boys with FXS and DS have distinctive language profiles. Although both groups demonstrated syntactic delays, boys with DS showed greater delays.
authors.affiliation: Frank Porter Graham Child Development Institute, University of North Carolina at Chapel Hill, USA. jprice@muw.edu
authors.forename: Johanna R
authors.initials: JR
authors.lastname: Price
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Roberts
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Hennon
authors.forename: Mary C
authors.initials: MC
authors.lastname: Berni
authors.forename: Kathleen L
authors.initials: KL
authors.lastname: Anderson
authors.forename: John
authors.initials: J
authors.lastname: Sideris
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000235:genetics / Q000503:physiopathology*; D005600:Fragile X Syndrome / Q000235:genetics / Q000503:physiopathology*; D005838:Genotype; D006801:Humans; D007805:Language Development Disorders / Q000235:genetics / Q000503:physiopathology*; D007807:Language Tests; D008037:Linguistics; D008297:Male; D010641:Phenotype