Abstract
Heritability estimates for specific language impairment (SLI) have been inconsistent. Four twin studies reported heritability of 0.5 or more, but a recent report from the Twins Early Development Study found negligible genetic influence in 4-year-olds. We considered whether the method of ascertainment influenced results and found substantially higher heritability if SLI was defined in terms of referral to speech and language pathology services than if defined by language test scores. Further analysis showed that presence of speech difficulties played a major role in determining whether a child had contact with services. Childhood language disorders that are identified by population screening are likely to have a different phenotype and different etiology from clinically referred cases. Genetic studies are more likely to find high heritability if they focus on cases who have speech difficulties and who have been referred for intervention.
| Original language | English |
|---|---|
| Pages (from-to) | 365-372 |
| Number of pages | 8 |
| Journal | Genes brain and behavior |
| Volume | 7 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Apr 2008 |
Keywords
- etiology
- heritability
- specific language impairment
- speech
- twins
- SPEECH-SOUND DISORDER
- GENETIC INFLUENCES
- IDENTIFYING CHILDREN
- DEVELOPMENTAL SPEECH
- 6-YEAR-OLD TWINS
- 4-YEAR-OLD TWINS
- ETIOLOGY
- SKILLS
- DIFFICULTIES
- MULTIVARIATE