Supportive evidence for the DYX3 dyslexia susceptibility gene in Canadian families

Open Access
Publisher Website
Google Scholar
Abstract
As described in detail elsewhere,3, 4 our sample consists of 96 Canadian families (877 subjects), each containing two or more sibs diagnosed with phonological coding dyslexia (PCD). This diagnosis was used since the key problem in most reading disabled subjects is a specific difficulty in the phonological coding component of reading, where written words are sounded out using grapheme-phoneme (letter-sound) rules. The PCD diagnosis (affected, unaffected, or uncertain) was determined for all subjects primarily based on psychometric test results for phonological coding. Test results for phonological awareness, which is the ability to recognise and manipulate phonemes, and for spelling, which requires phonological and orthographic (recognition of letter patterns) coding, were used to assist in diagnosis, as was reading history for adults. The PCD phenotype was used for parametric and non-parametric linkage analyses. Scores from the phonological awareness, phonological coding, and spelling tests were used in quantitative trait variance component linkage analyses, after conversion to standard scores (for phonological coding and spelling) or age adjustment (for phonological awareness). Of the 96 families, 46 were nuclear families consisting of both parents, two or more affected children, and unaffected children if available, with an average family size of five members. The remaining 50 families were extended kindreds consisting of a nuclear family and other branches with affected and unaffected relatives, ranging in size from six to 107 members (average 18 members). Seven microsatellite markers spanning the DYX3 region were selected from the report of Fagerheim et al1 and automated genotyping was performed using a LI-COR 4200S-2 Gene ReadIR DNA Analyzer. Marker allele frequencies were calculated from the parents of one nuclear family per pedigree. The Genethon genetic map5 was used for intermarker order and distances: (pter) D2S1352 - 4 cM - D2S2352 - 1 cM - D2S378 - 0 cM - D2S2279 - 0 cM - D2S2183 - 1 cM - D2S1337 - 2 cM - D2S393 (cen). This marker order corresponded to the order from the human genome sequence.6

This publication has 0 references indexed in Scilit: