Objective: The authors previously identified a haplotype on chromosome 6p22 defined by three single-nucleotide polymorphisms (SNPs) that was associated with dyslexia (reading disability) in two independent samples of families that included at least one sibling with severe reading impairment. The authors also showed that this haplotype is associated with a reduction in expression of the KIAA0319 gene. In addition, a completely independent study detected an association between KIAA0319 markers and reading disability. In the current study, the authors tested whether the KIAA0319 gene influences reading skills in the general population, rather than having an effect restricted to reading disability.
Method: The authors genotyped four SNPs that previously showed association with reading disability in the population of 7-9-year-old children in the Avon Longitudinal Study of Parents and Children (ALSPAC), a large longitudinal cohort for which reading-related phenotypes were available for more than 6,000 individuals. The authors conducted quantitative analysis for both single markers and haplotypes.
Results: The rs2143340 SNP, which effectively tags the three-SNP risk haplotype, was significantly associated with a test for reading ability. The risk haplotype itself also showed association with poor reading performance, and as in previous research, the association was stronger when the analysis was controlled for IQ.
Conclusions: These results both support a role of the KIAA0319 gene in the development of dyslexia and suggest that this gene influences reading ability in the general population. Moreover, the data implicate the three-SNP haplotype and its tagging SNP rs2143340 as genetic risk factors for poor reading performance.