These findings suggest that the phenotype for CAS changes with age. Language disorders persist in these children despite partial resolution of articulation problems. Children with CAS are also at risk for reading and spelling problems.
Speech-sound disorder (SSD) is a complex behavioral disorder characterized by speech-sound production errors associated with deficits in articulation, phonological processes, and cognitive linguistic processes. SSD is prevalent in childhood and is comorbid with disorders of language, spelling, and reading disability, or dyslexia. Previous research suggests that developmental problems in domains associated with speech and language acquisition place a child at risk for dyslexia. Recent genetic studies have identified several candidate regions for dyslexia, including one on chromosome 3 segregating in a large Finnish pedigree. To explore common genetic influences on SSD and reading, we examined linkage for several quantitative traits to markers in the pericentrometric region of chromosome 3 in 77 families ascertained through a child with SSD. The quantitative scores measured several processes underlying speech-sound production, including phonological memory, phonological representation, articulation, receptive and expressive vocabulary, and reading decoding and comprehension skills. Model-free linkage analysis was followed by identification of sib pairs with linkage and construction of core shared haplotypes. In our multipoint analyses, measures of phonological memory demonstrated the strongest linkage (marker D3S2465, P=5.6 x 10(-5), and marker D3S3716, P=6.8 x 10(-4)). Tests for single-word decoding also demonstrated linkage (real word reading: marker D3S2465, P=.004; nonsense word reading: marker D3S1595, P=.005). The minimum shared haplotype in sib pairs with similar trait values spans 4.9 cM and is bounded by markers D3S3049 and D3S3045. Our results suggest that domains common to SSD and dyslexia are pleiotropically influenced by a putative quantitative trait locus on chromosome 3.
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.
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