Schematic for duplicon formation and dispersal in chromosomes 15q13, 15q11, and 16p11.2. At top is shown BAC 778A2 (AC004583) spanning the 5′ half of the ancestral HERC2 gene, which has undergone intrachromosomal duplications to form multiple duplicons in 15q13 and 15q11 (see Fig. 3d). Miropeats comparison of repeat-masked sequence to a chromosome 16p11.2 BAC 17E1 (AC002041) illustrates a transchromosomal duplication and transposition of aHERC2-duplicon (Miropeats displays regions of similarity by joining lines between two sequences). Note the 27.1 kb ofHERC2-like sequence duplicated between these two segments (BESTFIT alignment indicates 94.7% genomic identity). The 17E1 BAC also identifies a second gene segment derived from an ancestral Xq28 locus (the creatine transporter gene, SLC6A8). These and several other locally duplicated segments (as denoted by arcs) form additional duplicons in 16p11. 17E1 also has 4 interspersed repeats including a large CAGGG-rich region (see text).