overview of GWAS approaches see Neale and Purcell 2008), the GWAS method has not been exploited to the fullest, given its high financial costs (sample sizes of several thousands to ten-thousands may be needed, see for a recent discussion of this matter Burton et al. 2008). Major progress in the field came through a number of GWAS initiatives funded by government and industry, like the Welcome Trust Case Control Consortium (WTCCC; 2007) and the Genetic Association Information Network (GAIN; Manolio et al. 2007). Among the 13 diseases that were analyzed in the first rounds of these two initiatives, the WTCCC included 1 and GAIN included 4 psychiatric disorders.
