title: Children's history of speech-language difficulties: genetic influences and associations with reading-related measures.
abstract: OBJECTIVE
  This study examined (a) the extent of genetic and environmental influences on children's articulation and language difficulties and (b) the phenotypic associations between such difficulties and direct assessments of reading-related skills during early school-age years.
  
  
  METHODS
  Behavioral genetic analyses focused on parent-report data regarding the speech-language skills of 248 twin pairs (M = 6.08 years) from the Western Reserve Reading Project. In addition, phenotypic associations between children's speech-language status and direct assessments of early reading-related abilities were examined through hierarchical linear modeling (HLM).
  
  
  RESULTS
  Probandwise concordance rates and intraclass tetrachoric correlations indicated high heritability for children's difficulties in expressive language and articulation, with estimates of .54 and .97 accordingly. HLM results indicated that children with histories of speech-language difficulties scored significantly lower than unaffected children on various measures of early reading-related abilities.
  
  
  CONCLUSIONS
  Results from the parent-report survey provided converging evidence of genetic effects on children's speech and language difficulties and suggest that children with a history of speech-language difficulties are at risk for lower performance on early reading-related measures. The extent of risk differed across measures and appeared greatest for children who demonstrated a history of difficulties across articulation, expressive language, and receptive language. Implications for future genetic research and clinical practice are discussed.
authors.affiliation: Department of Speech and Hearing Science, University of Illinois at Urbana-Champaign, IL 61820, USA. lauras@uiuc.edu
authors.forename: Laura Segebart
authors.initials: LS
authors.lastname: DeThorne
authors.forename: Sara A
authors.initials: SA
authors.lastname: Hart
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Petrill
authors.forename: Kirby
authors.initials: K
authors.lastname: Deater-Deckard
authors.forename: Lee Anne
authors.initials: LA
authors.lastname: Thompson
authors.forename: Chris
authors.initials: C
authors.lastname: Schatschneider
authors.forename: Megan Dunn
authors.initials: MD
authors.lastname: Davison
mesh_terms: D001184:Articulation Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D002648:Child; D003147:Communication Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D004410:Dyslexia / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D006801:Humans; D007806:Language Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D008297:Male; D010641:Phenotype; D012720:Severity of Illness Index; D013064:Speech Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D014427:Twins / Q000235:genetics*