Next, we performed a joint analysis of the discovery and psychosis follow-up sets. To account for testing two phenotypes (schizophrenia and psychosis), the genome-wide significance threshold was set at P < (5 × 10−8)/2, or 2.5 × 10−8. Five SNPS, residing at three loci, exceeded this threshold (Supplementary Table 3). Two of the loci—the MHC region and 11q21.2 near NRGN—had been genome-wide significant in the previous schizophrenia analysis; a third locus, in TAOK2 at 16p11.2, was novel (Supplementary Table 3). Following the addition of data from a further 1,014 schizophrenia cases and 1,144 controls, the variant at the novel locus, rs4583255[T], was associated with psychosis with increased significance (OR = 1.08, P = 6.6 × 10−11, Table 1). rs4583255[T]’s association with psychosis fit the multiplicative model (P = 0.42), and there was no evidence of OR heterogeneity (P = 0.71, I2 = 0, Supplementary Table 4).
