Journal article
Heritability of Specific Language Impairment and Nonspecific Language Impairment at Ages 4 and 6 Years Across Phenotypes of Speech, Language, and Nonverbal Cognition
Journal of speech, language, and hearing research, Vol.63(3), pp.793-813
03/01/2020
DOI: 10.1044/2019_JSLHR-19-00012
PMCID: PMC7229710
PMID: 32163317
Abstract
Purpose
Early language and speech acquisition can be delayed in twin children, a twinning effect that diminishes between 4 and 6 years of age in a population-based sample. The purposes of this study were to examine how twinning effects influence the identification of children with language impairments at 4 and 6 years of age, comparing children with specific language impairment (SLI) and nonspecific language impairment (NLI); the likelihood that affectedness will be shared within monozygotic versus dizygotic twin pairs; and estimated levels of heritability for SLI and NLI. Twinning effects are predicted to result in elevated rates of language impairments in twins.
Method
The population-based twin sample included 1,354 children from 677 twin pairs, 214 monozygotic and 463 dizygotic, enrolled in a longitudinal study. Nine phenotypes from the same comprehensive direct behavioral assessment protocol were investigated at 4 and 6 years of age. Twinning effects were estimated for each phenotype at each age using structural equation models estimated via diagonally weighted least squares. Heritabilities were calculated for SLI and NLI.
Results
As predicted, the twinning effect increased the percentage of affected children in both groups across multiple language phenotypes, an effect that diminished with age yet was still not aligned to singleton age peers. Substantial heritability estimates replicated across language phenotypes and increased with age, even with the most lenient definition of affectedness, at −1
SD
. Patterns of outcomes differed between SLI and NLI groups.
Conclusions
Nonverbal IQ is not on the same causal pathway as language impairments. Twinning effects on language acquisition affect classification of 4- and 6-year-old children as SLI and NLI, and heritability is most consistent in the SLI group. Clinical practice requires monitoring language acquisition of twins to avoid misdiagnosis when young or a missed diagnosis of language impairments at school entry.
Details
- Title: Subtitle
- Heritability of Specific Language Impairment and Nonspecific Language Impairment at Ages 4 and 6 Years Across Phenotypes of Speech, Language, and Nonverbal Cognition
- Creators
- Mabel L. Rice - University of KansasCatherine L. Taylor - University of Western AustraliaStephen R. Zubrick - Telethon Kids InstituteLesa Hoffman - University of IowaKathleen K. Earnest - University of Kansas
- Resource Type
- Journal article
- Publication Details
- Journal of speech, language, and hearing research, Vol.63(3), pp.793-813
- Publisher
- Amer Speech-Language-Hearing Assoc
- DOI
- 10.1044/2019_JSLHR-19-00012
- PMID
- 32163317
- PMCID
- PMC7229710
- ISSN
- 1092-4388
- eISSN
- 1558-9102
- Language
- English
- Date published
- 03/01/2020
- Academic Unit
- Psychological and Quantitative Foundations
- Record Identifier
- 9984371080102771
Metrics
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