CNV studies have now established a significant role for rare (<1% in frequency) and large (>100kb) CNVs in risk for schizophrenia (Sebat et al., 2009). Early findings from our group observed a 3-fold enrichment of rare genic CNVs in cases as compared with controls (Walsh et al., 2008). In a larger study by the International schizophrenia Consortium, a 1.1–1.5 fold enrichment was observed in cases (International schizophrenia Consortium, 2008). These findings have been supported by several subsequent studies (Buizer-Voskamp et al., 2011; Kirov et al., 2009), confirming that rare CNVs are collectively more common in schizophrenia cases compared to controls.
