C4A and schizophrenia: Recently, a portion of the risk in the HLA region has been attributed to relatively frequent copy-number variation (CNV) spanning the C4A-C4B complement genes, and the gene expression analysis of post-mortem tissues from several brain regions indicated that the C4A gene is over expressed among patients with schizophrenia.47 These analyses also indicate additional, independently acting risk variants in the HLA region.47 Similarly, our analyses pointed to additional SNPs in HLA that should be explored further.