Product Description:
Language impairment, reading disability, and speech sound disorder are developmental disorders with separate clinical definitions but which often occur together in children, and this comorbidity may be due in part to common genetic influences. Our previous linkage analyses in a population of children selected for language impairment replicated the linkage of reading and language phenotypes to microsatellite markers on chromosome 6p22 in the DYX2 region. The linked markers flanked the two candidate genes for reading disability, DCDC2 and KIAA0319. To confirm this finding and determine if one or both of the candidate genes were involved in language impairment, we followed up with 36 SNPs spanning the genes VMP, DCDC2, KIAA0319, and TTRAP. The subjects were the nuclear families of probands from 86 families totaling 220 children who have been involved in longitudinal language studies by Dr. Rice. The probands were ascertained from speech/language pathologists and were screened for intelligence in the normal range, normal hearing, intelligible speech, and language disability using standardized criteria. Eight phenotypes were evaluated in the children, including measures of language, grammatical morphology, reading, and articulation. Using FBAT analysis (additive hypothesis), only 5 SNPs showed significant association, and all of these were in or near KIAA0319. Three of these SNPs have previously been reported to show association with reading phenotypes in other studies (e.g., Francks et al., 2004; Cope et al., 2005; Luciano et al., 2007), and the same alleles were found to be associated with reading and language problems in our study. These SNPs are in the 5? region and first intron of KIAA0319, suggesting that their association is with elements that regulate the level of expression of the gene.
