Visualization of insertion and deletion events in the human genome. Miropeats (99) comparison of the sequences of (a) fosmid WIBR2–647I01 showing a 12-kb insertion, and (b) fosmid WIBR2–1263I16 showing a 14-kb deletion (16), with the corresponding regions of hg17 of the human genome reference assembly (chr15:64,167,000–64,192,000 and chr19:56,805,000–56,857,000, respectively). Lines connect regions of identity both within and between the human genome assembly (top) and the fosmid sequence (bottom), allowing the structure to be visualized. (a) BLAT analysis shows that the 12-kb region inserted in fosmid WIBR2–647I01 is a novel sequence not represented in the human genome reference assembly, and would thus be undetectable by techniques other than paired-end sequence mapping. (b) Note the presence of homologous sequences (comprising a 300-bp GT-rich repeat and a 400-bp duplicated sequence) precisely flanking the deletion region, consistent with the hypothesis that the duplication architecture of the human genome predisposes to structural rearrangement by nonallelic homologous recombination.