Search

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. Supplemental Material https://doi.org/10.23641/asha.6170354

The purpose of this article is to review recent findings suggesting a genetic susceptibility for speech sound disorders (SSD), the most prevalent communication disorder in early childhood. The importance of genetic studies of SSD and the hypothetical underpinnings of these genetic findings are reviewed, as well as genetic associations of SSD with other language and reading disabilities. The authors propose that many genes contribute to SSD. They further hypothesize that some genes contribute to SSD disorders alone, whereas other genes influence both SSD and other written and spoken language disorders. The authors postulate that underlying common cognitive traits, or endophenotypes, are responsible for shared genetic influences of spoken and written language. They review findings from their genetic linkage study and from the literature to illustrate recent developments in this area. Finally, they discuss challenges for identifying genetic influence on SSD and propose a conceptual framework for study of the genetic basis of SSD.

This study used a cross-sectional design to examine the performance of people with a history of a preschool phonology disorder on measures of phonology, reading, and spelling at preschool age ( n =20), grade school age ( n =23), adolescence ( n =17), and adulthood ( n =17). Results showed that at each age group, subjects with a history of a disorder performed more poorly than control subjects matched for age, sex, and socioeconomic status in all domains. Comparisons across each successive age group revealed a higher performance on measures from preschool to grade school age, and a smaller but steady improvement from grade school age to adolescence to adulthood. Subjects with a history of other language problems, in addition to the phonology disorder overall, performed more poorly than subjects with a history of a preschool phonology disorder alone on the reading and spelling measures. These findings suggest that remnants of a preschool phonology disorder are detectable past grade school age and into adulthood.