The genomewide association study (GWAS), with up to 1 million single nucleotide polymorphisms (SNPs) genotyped, is currently the most powerful, systematic and unbiased genetic approach to the study of the common disease/common variant (CDCV) hypothesis of complex disorders like schizophrenia. Since the initial suggestion by Risch and Merikangas of the power of association methods for human diseases3, GWAS have successfully identified novel associations and/or replicated prior susceptibility genes for a number of complex traits, including age-related macular degeneration4, Type 15 and Type 26–11 diabetes, episodic memory12, Crohn’s disease13–16, prostate cancer17–19 and obesity20.
