Chromosomal Microarray Analysis in Taiwanese Patients with Williams-Beuren Syndrome

Williams-Beuren Syndrome (WBS; OMIM #194050) is a rare neurodevelopmental disorder that results from a deletion at 7q11.23 spanning 25-27 genes. We performed chromosomal microarray analysis (CMA) in 9 Taiwanese patients with WBS to confirm the diagnosis. These samples had already been examined by FISH and diagnosed as WBS. Pathogenic copy number variations (CNVs) were identified in all patients, including 24 genes (spanning from FKBP6 to GTF2I) with typical 7q11.23 microdeletion. A deletion in TRIM50 was common in Taiwanese patients with WBS (8/9). Furthermore, 1 patient had 2 additional gene deletions in NCF1 and GTF2IRD2. We also found 4 patients with duplications of 4p16.1, 16p13.11, 10q26.3, and 21q22.3. All 9 WBS patients exhibited distinctive facial dysmorphisms, including a wide mouth, thick prominent lips, short nose with anteverted nares, and periorbital puffiness. However, cardiac defects were not frequent in our patients (3/9). In conclusion, we detected CNVs associated with WBS in a Taiwanese population using CMA. Although CMA is expensive and labor-intensive, it is useful for identifying typical/atypical CNVs, delineating distal break points, and detecting other CNVs.