De novo CNVs were significantly associated with BD and SCZ (Table 2). The rate of de novo mutation in controls was 0.9% (4/426). This rate is consistent with estimates from previous studies ranging from 0.5% to 3% (Conrad et al., 2010, Itsara et al., 2010, Levy et al., 2011, Sebat et al., 2007 and Xu et al., 2008). The observed rate of de novo CNVs in bipolar disorder subjects was 4.3% (8/185), a significant enrichment compared with controls (p = 0.009, OR = 4.8 [1.4,16.0]). De novo CNVs were also detected at a significantly higher rate (8/177, 4.5%) in schizophrenia subjects than in controls (p = 0.007, OR = 5.0 [1.5,16.8]). These results provide significant evidence for an association of de novo mutation with bipolar disorder and confirm earlier reports of a high rate of de novo copy-number mutation in schizophrenia (Xu et al., 2008).
