After genotyping five SNPs in APBB1 and observing several preliminary positive findings, we found only SNP rs4758416 remained significantly associated with SQ and HSI in the pooled sample after correction for multiple testing, providing further evidence of nominal association of rs4758416 with ND observed in each ethnic-specific sample. In addition, we found three major haplotypes significantly associated with ND after Bonferroni correction. Two halpotypes, C-C-T and G-C-T, consisting of rs4758416-rs10839562-rs1079199, showed significant associations with at least one ND measure in one of the three samples. C-C-T appears to be a risk haplotype for ND, while G-C-T seems to function as a protective haplotype. A comparison of the two haplotypes with opposite genetic effects on ND behaviors reveals they are primarily determined by rs4758416, suggesting this region may harbor causative SNP(s) affecting ND. Another haplotype, C-T-G, formed by rs10839562-rs1079199-rs8164, showed a significant protective effect in ND as measured by HSI in the EA sample.
