None of the SNPs that were nominally significant (P ≤ 0.05) in both AAs and EAs can survive multiple testing correction in the discovery stage of association analysis under the linkage peak using the SAGE dataset. However, our prioritization strategy, designed to order SNPs for follow up studies, relies on both statistical evidence and prior knowledge. Accordingly, the SNP rs17664708 located at NRG1 was prioritized for further studies. NRG1 is a well established susceptibility gene for schizophrenia in many populations supported by genetic linkage, association studies, and meta-analysis (55–57). There are at least three lines of prior knowledge which prompt us to consider NRG1 as a candidate gene for CaD as well. First, elevated rates of cannabis use have repeatedly been reported among individuals with schizophrenia (49, 50), and epidemiological studies suggest that frequent cannabis use is associated with about 2-fold increased risk for developing schizophrenia and related disorders (7,8,51–53). The significant commorbidity between cannabis use and schizophrenia may be attributable in part to a shared underlying genetic component for CaD and schizophrenia. Second, the neurobiology of CaD and schizophrenia
