Our findings, thus, suggest that the RDC schizoaffective disorder, bipolar type set of cases is likely to be particularly fruitful for genetic investigations aimed at identifying common polymorphisms that influence risk (i.e. the type of genetic variants that genome-wide association studies are designed to detect). If our findings generalise to other samples, it would suggest that careful phenotypic selection of participants could enhance power to identify genes conferring susceptibility to illness. At present there is a great deal of effort being invested in rapidly assembling the large samples of individuals with psychiatric illness that are expected to be necessary to provide power to detect susceptibility genes. The current findings suggest that it will also be important to pay sufficient attention to the phenotype so that genetically relevant distinctions can be made.
