Further evidence for a susceptibility locus contributing to reading disability on chromosome 15q15-q21

Background Linkage and association studies in dyslexia suggest that a susceptibility locus exists on chromosome 15q15-q21. Objective This study aims to evaluate these findings in an independent sample of dyslexia. Methods We performed linkage and association analyses using 82 families with dyslexia and 19 STR markers covering the target region on chromosome 15q. Results We observed suggestive evidence for linkage at STR-marker D15S143; this was the strongest implicated marker in the previous linkage studies on dyslexia. At the association level, linkage disequilibrium (LD) was found between dyslexia and markers within a circumscribed genomic region recently implicated in two independent studies on dyslexia. Conclusion Our data and the previous reported findings present convincing evidence for a dyslexia-related gene within the identified linkage and LD region on chromosome 15q. However, at this stage it seems difficult to determine whether the linkage and association findings point to more than one susceptibility loci within this region. A definite answer to this question will require systematic single nucleotide polymorphism-based LD mapping within the implicated region, which should lead to the identification of the true dyslexia susceptibility gene(s).