Williams-Beuren syndrome diagnosis using fluorescence in situ hybridization.

Williams-Beuren syndrome (WBS) is most commonly caused by a 1.5-Mb hemizygous deletion of chromosome 7q 11.23. Other genomic rearrangements of this region have also been described, some as polymorphisms and others as rare variants, the latter often being directly associated with clinical symptoms. Fluorescence in situ hybridization of either metaphase or interphase nuclei can be used to detect all of these chromosomal rearrangements, providing the ability to test this segment of chromosome 7 in families with a suspected diagnosis of WBS.