Our linkage analysis revealed two novel regions of linkage, 6q27 (LOD = 2.94) and 20p13 (LOD = 3.81), with the latter formally exceeding the threshold for genome-wide significance. There is some overlap between the more modest signals (LOD > 2 on chr15 and chr17) and previously reported suggestive signals, but little overlap with the most promising regions of common SNP association. This suggests that the regions of the genome showing linkage may harbor rare variation, potentially with allelic heterogeneity across families, which would require re-sequencing to uncover, as has been demonstrated for the 7q35 region17,18,19. Interestingly, several of these regions overlap with rare syndromes or genetic events known to be strong risk factors for autism. For example, an autism case with a translocation disrupting 15q25 has been reported, while the 17p region overlaps the Smith Magenis and Potocki-Lupski Syndrome region.
