No SNPs (or if not available, proxies in high LD) with previously reported associations were even nominally significant (p < .05) in our data. Note that not all SNPs mentioned in earlier studies were available in our dataset. A SNP in the gene CDH23 was listed by Terraciano et al. (2008) in association with Extraversion (p = 1.1*10−5); this gene had a gene-based association p-value with Novelty Seeking of .002 in our study. However, the gene effect was not significant in their study, and absent in the replication samples in their own study. None of the other genes were nominally significant in our data - in particular the DRD4 (Novelty Seeking) and SLC6A4 (Harm Avoidance) genes had p-values of 0.32 and 0.65, respectively. We calculated that our SNPs captured 52% of the variance in the DRD4 gene and 80% of the variance in the SLC6A4 gene. We did this by identifying the overlap between our SNPs and all SNPs within 50kb of the genes (as per HapMap Genome Browser) and then calculating what proportion of the total variance of the gene our SNPs covered using the Tagger option in Haploview (selecting SNPs with a MAF > 0.05 only).
