Past experience suggests that for some disorders, as many as 20,000-30,000 cases and a similar number of controls (or case-parent trios) could be required to obtain highly robust findings. More datasets will be genotyped in the near future, and NIMH plans to collect additional large schizophrenia and bipolar disorder samples (http://grants.nih.gov/grants/guide/rfa-files/RFA-MH-08-131.html). This raises important questions of resource allocation. For example, the next phase of genetic studies will involve a combination of increasingly large GWAS analyses (for common SNP and CNV associations) and resequencing studies (for rare variants). It is not known how these and other research investments should be optimally balanced.
