Utilizing the SAGE GWAS dataset, we examined the genetic association between CaD and 4853 SNPs under the strongest linkage peak from our family sample (lod > 2, from 48.9 cM to 65.2 cM) on chromosome 8. All of these SNPs passed QC and were tested for genetic association with adjustment for sex, age and the top 10 PCs in AAs and EAs separately. Eleven SNPs were nominally significantly associated with CaD in both AAs and EAs (Table 2). One SNP (rs17664708), which is relatively rare in AA controls (MAF = 0.02) but common in EA controls (MAF=0.096), showed consistent evidence for association in both AAs (OR=2.93, 95% CI=1.47–5.85, P=0.0022) and EAs (OR=1.38, 95% CI=1.05–1.81, P=0.02). This SNP is located at NRG1, which has been previously implicated in the risk for schizophrenia. Considering the high degree of commorbidity between cannabis use and schizophrenia (7, 8, 49–53), this SNP (rs17664708) was prioritized for further study.
