Rs807701, a SNP in the DCDC2 gene, is in a region that crops up in several independent studies as likely to associated with dyslexia. The risk allele in the Caucasian populations studied is (C).
One study reports that the odds ratio for rs807701 genotypes increases if calculated from subsets of more severely dyslexic individuals as compared to more heterogenous, larger groups of dyslexic individuals. The genotype relative risk (GRR) for rs807701(C;C) increased from 1.88 (95% CI 0.89-3.97; P=.058) for the larger group up to 5.04 (95% CI 1.35-18.88; P=.002) for the most severely affected group. [PMID 16385449]
Combined with another SNP marker in the DCDC2 gene, rs793862, the (haplotype) GRR also increased for the homozygous haplotype rs793862(A)-rs807701(C), from 4.11 (95% CI 2.77-6.08; P<.0001) for the larger group, up to 11.13 (95% CI 6.32-19.60; P<.0001) for the most severely affected group. [PMID 16385449]
[PMID 19238550] The role of gene DCDC2 in German dyslexics.