Do Genes Associated with Dyslexia of Chinese Characters Evolve Neutrally?

Abstract

Dyslexia, or reading disability, is found to have a genetic basis, and several related genes have been reported. We investigated whether natural selection has acted on single nucleotide polymorphisms (SNPs) that were reported to be associated with risk/non-risk for the reading disability of Chinese characters. We applied recently developed 2D SFS-based statistics to SNP data of East Asian populations to examine whether there is any sign of selective sweep. While neutrality was not rejected for most SNPs, significant signs of selection were detected for two linkage disequilibrium (LD) regions containing the reported SNPs of GNPTAB and DCDC2. Furthermore, we searched for a selection target site among the SNPs in these LD regions, because a causal site is not necessarily a reported SNP but could instead be a tightly linked site. In both LD regions, we found candidate target sites, which may have an effect on expression regulation and have been selected, although which genes these SNPs affect remains unknown. Because most people were not engaged in reading until recently, it is unlikely that there has been selective pressure on reading ability itself. Consistent with this, our results suggest a possibility of genetic hitchhiking, whereby alleles of the reported SNPs may have increased in frequency together with the selected target, which could have functions for other genes and traits apart from reading ability.

Potential Logographic Dyslexics Identified via Self-Reporting during a Questionnaire Survey in Taiwan

“…This may be related to hypothalamic-pituitary-adrenal (HPA) axis [4]. The two daughters of case D3 both experienced difficulties for schooling, suggesting that the genes are involved [20,21]. D3 could not learn to ride a bicycle supports the cerebellum theory for dyslexia [23][24][25].…”

“…Researchers proposed that the genotypes cause the functional changes of the brain and generates the cognitive and perceptive deficits in dyslexics [18]. The predominant opinions agree that genes [19][20][21] and brain [16] are two areas to focus on [22]. The potential risk loci located on chromosome 1, 2,3,4,6,11,12,13,15,17,18, and X [19].…”