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. 2019 Aug 14;56(12):801–808. doi: 10.1136/jmedgenet-2019-106080

Figure 2.

Figure 2

Schematic representation of the Williams-Beuren syndrome (WBS) locus, showing the two most common deletions and the gene content of the B block. The B block contains three genes: GTF2I, NCF1 and GTF2IRD2. Whereas GTF2I and NCF1 have a single functional copy located at the medial B block, GTF2IRD2 has two functional copies, located at the medial (GTF2IRD2) and telomeric (GTF2IRD2B) B blocks. The 1.55 Mb deletion is mediated by B blocks and results in a chimeric medial-centromeric block, with the number of functional copies of GTF2IRD2 and NCF1 depending on the deletion breakpoint. In contrast, the 1.83 Mb deletion is mediated by A blocks, resulting in the loss of the medial and centromeric B blocks with functional copies of GTF2IRD2 and NCF1.