We examined the linkage disequilibrium (LD) pattern among the eight replicated SNPs with improved P-values (Figure 3) to gain a better understanding of the association. Seven of these SNPs form two tightly linked LD blocks. Given that none of these SNPs reside within known genes or known regulatory sequences, the clustering of association signals suggests that one or more nearby functional variants is responsible for the signal. A survey of the genomic landscape surrounding this region of association reveals several interesting avenues for further molecular investigation. There are numerous sequence segments exhibiting a high degree of evolutionary conservation, suggesting potential regulatory, but currently undetermined, functions. In addition, there are three known copy number variants (CNVs) in proximity of the most significant SNPs (Table 2). Preliminary investigation of these CNVs in the discovery dataset is not suggestive of a causal relationship with autism (data not shown). Exhaustive molecular analysis of the candidate region is ongoing. In addition, although the immediate 1 Mb vicinity of the association region contains no known genes, flanking the region are CDH9 and CDH10, two genes belonging
