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. Author manuscript; available in PMC: 2010 Jun 22.
Published in final edited form as: Nat Genet. 2001 Nov;29(3):321–325. doi: 10.1038/ng753

Fig. 5.

Fig. 5

A new NotI–PFGE restriction fragment in individuals carrying the WBS inversion. NotI-digested genomic DNA from families with WBS was fractionated by PFGE and examined by blot-hybridization analysis using a GTF2I-specific probe (corresponding to the 3′ UTR of GTF2I; nt 2134–2638 of GenBank NM_032999). A representative result with resolution of fragments in the 450 kb–1.6 Mb range is shown. We observed a new NotI junction fragment only in those individuals (8580, 11107, 9912, 12503) shown by FISH to carry the WBS inversion. In normal individuals, the GTF2I probe should detect NotI fragments 3 Mb and 1 Mb in size on the centromeric and telomeric side of the WBS region, respectively. Note that GTF2I is present at each end of the WBS region and therefore hybridizes to two NotI fragments (see Fig. 1)23. Our results (lane 2, WBS proband 8579) and those previously published23 show that the 1.5-Mb microdeletion observed in individuals with WBS leads to the formation of a 4-Mb junction fragment, in addition to the 3-Mb and 1-Mb NotI fragments present on nondeleted (normal) chromosomes. The 3-Mb and 4-Mb NotI fragments remain in the compression zone on this gel; the 1-Mb band is visible (lane 2). In carriers of the WBS inversion, the NotI junction fragment is in the 500–600 kb range. This size is consistent with what would be predicted if the inversion breakpoints occurred within the duplicons, as was known to be the case based on our FISH results (see Fig. 1). Such an event would lead to a reduction in size of the 1-Mb NotI-fragment on the rearranged chromosome, as we observed when probing with GTF2I (the identity of the new 500–600-kb fragment was also confirmed by hybridization with an HIP1-gene probe). The extent in reduction of size of the 1-Mb NotI fragment would depend on the site of the inversion breakpoint(s) within the duplicon. In parent 8581 with WBS (lane 4), who does not carry the inversion, we observed a 1.1-Mb NotI fragment in addition to the normal 1-Mb fragment. This may be due to size polymorphism within the WBS region occurring on one chromosome.