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Open Access Research article

Copy number variation in Williams-Beuren syndrome: suitable diagnostic strategy for developing countries

Roberta L Dutra123*, Rachel S Honjo1, Leslie D Kulikowski2, Fernanda M Fonseca3, Patrícia C Pieri3, Fernanda S Jehee1, Debora R Bertola1 and Chong A Kim1

Author Affiliations

1 Department of Genetics, Instituto da Criança, Universidade de São Paulo, São Paulo, Brazil

2 Department of Pathology, LIM 03, Universidade de São Paulo, São Paulo, Brazil

3 Laboratory of Genomic Pediatrics - LIM 36, Instituto da Criança, Universidade de São Paulo, São Paulo, Brazil

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BMC Research Notes 2012, 5:13  doi:10.1186/1756-0500-5-13

Published: 9 January 2012

Abstract

Background

Williams-Beuren syndrome (WBS; OMIM 194050) is caused by a hemizygous contiguous gene microdeletion at 7q11.23. Supravalvular aortic stenosis (SVAS), mental retardation, and overfriendliness comprise typical symptoms of WBS. Although fluorescence in situ hybridization (FISH) is considered the gold standard technique, the microsatellite DNA markers and multiplex ligation-dependent probe amplification (MLPA) could be used for to confirm the diagnosis of WBS.

Results

We have evaluated a total cohort of 88 patients with a suspicion clinical diagnosis of WBS using a collection of five markers (D7S1870, D7S489, D7S613, D7S2476, and D7S489_A) and a commercial MLPA kit (P029). The microdeletion was present in 64 (72.7%) patients and absent in 24 (27.3%) patients. The parental origin of deletion was maternal in 36 of 64 patients (56.3%) paternal in 28 of 64 patients (43.7%). The deletion size was 1.55 Mb in 57 of 64 patients (89.1%) and 1.84 Mb in 7 of 64 patients (10.9%). The results were concordant using both techniques, except for four patients whose microsatellite markers were uninformative. There were no clinical differences in relation to either the size or parental origin of the deletion.

Conclusion

MLPA was considered a faster and more economical method in a single assay, whereas the microsatellite markers could determine both the size and parental origin of the deletion in WBS. The microsatellite marker and MLPA techniques are effective in deletion detection in WBS, and both methods provide a useful diagnostic strategy mainly for developing countries.