Figure 1

22q11.21 and 15q11-q13 regions. A. Schematic representation of chromosome 22q11.21 showing the genes in the region, the common recurrent deletions (red bars), and the segmental duplications that mediate the rearrangements (blue rectangles), termed low copy repeat (LCR) A to D. B. Schematic representation of the 15q11-q13 region deleted in Prader-Willi and Angelman syndromes. Paternally expressed genes are shown in yellow, maternally expressed genes in orange. Recurrent deletions are represented as red bars; the segmental duplications that mediate the rearrangements, termed breakpoint (BP) 1 to 3, are portrayed as blue rectangles.