We did not observe genome-wide significant association (P < 5 × 10−8) to ASDs in the AGRE cohort, but we proposed that meaningful associations were contained within the lowest P values. To boost power for identifying these associations, we examined an Autism Case-Control cohort (ACC cohort, Table 1), comprising 1,453 subjects with ASDs from several US sites, and 7,070 control subjects without ASDs from the Children's Hospital of Philadelphia, who were also genotyped on the same platform. The subjects with ASDs in this cohort were diagnosed using the ADI and ADOS tools. After conducting thorough quality control measures on the geno-types, association analyses were conducted on 1,204 subjects with ASDs and 6,491 control subjects of inferred European ancestry. We did not detect genome-wide significant association (P < 5 × 10−8) to ASDs in the ACC cohort either. Therefore, we subsequently performed a combined analysis of these two independent data sets using recommended meta-analysis approaches24. From examining autosomes and the X chromosome, one SNP located on 5p14.1 reached genome-wide significance (rs4307059, P = 3.4 × 10−8), and five further SNPs at
