Test (PDT) (Martin et al. 2000, Martin, Bass & Kaplan 2001) was used for all association analyses. The distribution of p-values examined in the discovery dataset demonstrated a close match to that expected for a null distribution except at extreme tail of low p-values (Figure 1). This is expected if there is little residual error in the data and common variants of modest effect sizes are acting in autism. In the discovery dataset, none of the p-values met the stringent and overly conservative Bonferroni correction for genome-wide significance (Figure 2).
