Replication of reported linkages for dyslexia and spelling and suggestive evidence for novel regions on chromosomes 4 and 17

We report the first genome-wide linkage analysis for reading and spelling in a sample of 403 families of twins, aged between 12 and 25 years taken from the normal population and unselected for reading ability. These traits showed heritabilities of 0.52-0.73, and support for linkage exceeded replication levels (lod > 1.44) of seven of the 11 linkages reported in dyslexic samples, namely: 2q22.3, 3p12-q13, 6q11.2, 7q32, 15q21.1, 18p21, and Xq27.3. For five of these ( 2q22.3, 6q11.2, 7q32, 18p21, and Xq27), this study provides the first independent replication. 1p34-36 and 2p15-16 received some support, with lods of 1.2 and 0.83, respectively, whereas two regions received little support (6p23-21.3 and 11p15.5). This study also identified two novel linkages at 4p15.33-16.1 and 17p13.3, which received suggestive support ( max. lod 2.08 and 1.99, respectively).