In the current study, we found consistent evidence of both previously-reported ANK3 findings, and borderline support for replication of a region characterized at 15q14, although we failed to find support for the finding at CACNA1C. In ANK3 and at 15q14, multiple SNPs in weak to no linkage disequilibrium with the previously associated SNP showed stronger association. Investigation of haplotype-based associations in our study provides support for allelic heterogeneity in ANK3 region. Allelic heterogeneity has the potential to play an important role in genetically influenced disorders, yet can be difficult to detect in population-based samples using common variants, making it a potential explanation of “missing heritability” (30). Of note, and as we have previously indicated however, the Baum et al. (2008) and Sklar et al. (2008) samples both overlap with the current sample (15, 16), thus stringent conclusions pertaining to replication are not warranted.
