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JSLHR_Dec11_Lewis_supplemental_materials.pdf (143.67 kB)

Correlation Matrix of Measures Employed in the Structural Equation Model (Lewis et al., 2011)

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posted on 2011-12-01, 00:00 authored by Barbara A. Lewis, Allison A. Avrich, Lisa A. Freebairn, Amy J. Hansen, Lara E. Sucheston, Iris Kuo, H. Gerry Taylor, Sudha K. Iyengar, Catherine M. Stein
Purpose To demonstrate that early childhood speech sound disorders (SSD) and later school-age reading, written expression, and spelling skills are influenced by shared endophenotypes that may be in part genetic.
Method Children with SSD and their siblings were assessed at early childhood (ages 4–6 years) and followed at school age (7–12 years). The relationship of shared endophenotypes with early childhood SSD and school-age outcomes and the shared genetic influences on these outcomes were examined.
Results Structural equation modeling demonstrated that oral motor skills, phonological awareness, phonological memory, vocabulary, and speeded naming have varying influences on reading decoding, spelling, spoken language, and written expression at school age. Genetic linkage studies demonstrated linkage for reading, spelling, and written expression measures to regions on chromosomes 1, 3, 6, and 15 that were previously linked to oral motor skills, articulation, phonological memory, and vocabulary at early childhood testing.
Conclusions Endophenotypes predict school-age literacy outcomes over and above that predicted by clinical diagnoses of SSD or language impairment. Findings suggest that these shared endophenotypes and common genetic influences affect early childhood SSD and later school-age reading, spelling, spoken language, and written expression skills.


This research was supported by National Institute on Deafness and Other Communication Disorders Grant DC00528, awarded to Barbara A. Lewis, and National Center for Research Resources Grant KL2RR024990, awarded to Catherine M. Stein. Some of the results of this research were obtained using the program package S.A.G.E., which is supported by U.S. Public Health Service Resource Grant RR03655 from the National Center for Research Resources. We wish to express our appreciation to the speech-language pathologists who assisted us in recruiting subjects and to the families who generously agreed to participate.