Since our GWAS(4) was based upon fewer than 1/20th of all common SNPs in the genome, it seemed unlikely that the best associated SNP in our study was the true functional variant. In the present study, we tried to localize the association signal using a combination of de novo polymorphism discovery targeted at exons, pooled de novo polymorphism discovery spanning the genomic sequence of the locus, and high density LD mapping. rs1344706, the SNP originally highlighted by the original GWAS study, remained the most strongly associated SNP at the locus. The evidence for association for rs1344706 was further tested by a meta-analysis of around 60,000 subjects (schizophrenia/schizoaffective disorder N = 18945, schizophrenia plus bipolar disorder N =21274, controls N =38675) derived from the original publication and additional datasets. The overall statistical support in schizophrenia surpassed genome wide significance (P=2.5 ×10−11) by more than 3 orders of magnitude, as did the support in schizophrenia and bipolar disorder combined (P=4.1 ×10−13). Moreover, the evidence for association in replication samples (i.e. after exclusion of the discovery GWAS) was also genome wide significant, making
