Our initial approach focuses on recurrent events since they are more common and lend themselves to case-control analysis; future studies will focus on non-recurrent CNVs as large enough case numbers become available. Recurrent rearrangements mediated by segmental duplications were identified by comparison to previously described hotspot regions.9 Imbalances were considered recurrent if they included the critical region of the deletion/duplication event and, based on probe coverage, were likely mediated by paired, flanking segmental duplications. We carried out statistical analysis of 14 selected regions, including (see Table 1 for chromosome coordinates): 1q21 Thrombocytopenia-absent radius (TAR) region,10,11 distal 1q21.1,12,13 3q29,14,15 5q35,16,17 7q11.23,18,19 8p23.1,20,21 15q11.2-q13,22–24 15q13,25,26 16p13.11,27,28 16p11.2,29–31 17p11.2,32,33 17q12,34–36 17q21.3137–39 and 22q11.2.40,41 For the 1q21 regions, if the imbalance included both 1q21 TAR10 and the distal 1q21.1 region,12 the imbalance was included in the distal 1q21.112 frequency. In the 15q11q13 region, imbalances that spanned BP2 through BP542 were counted in the BP2-BP3 frequency and not the BP4-BP5 frequency. Both the smaller and larger rearrangements (~1.5 and ~3.0 Mb) for 16p13.1128 and 22q1143 were included in their respective CNV categories. For this study,
