Family-based association mapping provides evidence for a gene for reading disability on chromosome 15q.

Family-based association mapping was used to follow up reports of linkage between reading disability (RD) and a genomic region on chromosome 15q. Using a two-stage approach, we ascertained 101 (stage 1) and 77 (stage 2) parent-proband trios, in which RD was characterized rigorously. In stage 1, a set of eight microsatellite markers spanning the region of putative linkage was used and a highly significant association was detected between RD and a three-marker haplotype (D15S994/D15S214/D15S146: P and empirical P < 0.001). A significant association with the same three-marker haplotype was also observed in the second-stage sample (P = 0.009, empirical P = 0.006). Our data therefore provide strong evidence for one or more genes contributing to RD being located in the vicinity of the region including D15S146 and D15S994. In addition, our results provide support for association analysis being a useful method to map susceptibility loci for complex disorders.