A concurrent study of BD is being undertaken by the Pritzker Neuropsychiatric Disorders Research Consortium (PNDRC; Scott, Muglia, Upmanyu, Guan, Flickinger, Kong, Tozzi, Li, Burmeister, Absher et al., submitted). There is some overlap between the cases and controls used in our study and those used in the Pritzker study (407 EA cases and 357 EA controls). As an extension of our analyses we excluded these samples and repeated the association tests (see Table 1) so that the results of our study and the study by the PNDRC could be compared on the basis of independent samples. It is also the case that a portion of the samples on which we report here are not entirely independent of previously published BD GWA studies (15, 16). We were not, however, able to perform a similar analysis with the non-overlapping samples from these other studies due to restricted access to the genotype data and time constraints.
