As is expected in genome-wide association studies in a modestly sized sample,5 none of the association signals in our analysis of the RDC schizoaffective disorder, bipolar type data-set achieved accepted levels of genome-wide significance for European samples (P<7.2×10–8).35 Independent replication and meta-analysis will be required to confirm the role of any of the strongly associated loci in susceptibility to schizoaffective disorder. To date there has been no previous report of a systematic genetic association analysis of a set of individuals with schizoaffective disorder in comparison with controls. However, it is interesting to note that an analysis of the WTCCC bipolar disorder data-set that used a completely different analytic approach also identified the RDC schizoaffective disorder, bipolar type subset of participants as being of particular interest.36 That analysis used phenotype refinement of a specific genetic association signal of interest in the complete bipolar disorder and control data-set (at GABRB1) and found the signal to be maximal within the RDC schizoaffective disorder, bipolar type subset of participants. Testing of independent SNPs within genes encoding gamma amniobutyric acid (GABA)A receptors showed this set
