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Gene × Environment interactions in speech sound disorder predict language and preliteracy outcomes

  • Lauren M. McGrath (a1), Bruce F. Pennington (a1), Erik G. Willcutt (a2), Richard Boada (a3), Lawrence D. Shriberg (a4) and Shelley D. Smith (a5)...


Few studies have investigated the role of gene × environment interactions (G × E) in speech, language, and literacy disorders. Currently, there are two theoretical models, the diathesis–stress model and the bioecological model, that make opposite predictions about the expected direction of G × E, because environmental risk factors may either strengthen or weaken the effect of genes on phenotypes. The purpose of the current study was to test for G × E at two speech sound disorder and reading disability linkage peaks using a sib-pair linkage design and continuous measures of socioeconomic status, home language/literacy environment, and number of ear infections. The interactions were tested using composite speech, language, and preliteracy phenotypes and previously identified linkage peaks on 6p22 and 15q21. Results showed five G × E at both the 6p22 and 15q21 locations across several phenotypes and environmental measures. Four of the five interactions were consistent with the bioecological model of G × E. Each of these four interactions involved environmental measures of the home language/literacy environment. The only interaction that was consistent with the diathesis–stress model was one involving the number of ear infections as the environmental risk variable. The direction of these interactions and possible interpretations are explored in the discussion.


Corresponding author

Address correspondence and reprint requests to: Lauren M. McGrath, University of Denver, Department of Psychology, Frontier Hall, 2155 S. Race Street, Denver, CO 80209; E-mail:


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