Schematic representation of the genomic structure of the WBS locus at 7q11.23. There are three large segmental duplications or LCRs—centromeric (c), medial (m), and telomeric (t)—each of which is composed of three distinct blocks—A, B and C—represented by colored arrows that indicate their relative orientation with respect to each other. The most common WBS 1.55-Mb deletion arising from NAHR between blocks B is indicated. Note that block Cm is much shorter than blocks Cc and Ct, missing the darker green region that harbors BCSTR1. The locations of the relevant multiple- and single-copy markers used in this study are indicated on top of the scheme, while the MLPA probes and the BACs used as FISH probes are shown at the bottom.
