Abstract
Williams syndrome occurs with a frequency of 1 in 20,000. Clinical features of this syndrome include short stature, mental handicap, cardiac malformatons and a characteristic facies. Many patients are sporadic but autosomal dominant inheritance ia apparent in some families. Moreover, in many patients, chromosomal abnormalities are present. Williams syndrome belongs to a group of microdeletion syndromes meaning that in the vast majority of cases, the deletion is located on the long arm of chromosome 7 and it is visible on chromosomes only using molecular cytogenetic. In this study, we wanted to show that the deletion is visible by routine chromosome analysis in a significative number of cases. For this study, we have reviewed and reanalysed our cases of Williams syndrome by R-bands routine cytogenetic technique and proved by fluorescent in situ hybridyzation. The data obtained in this study showed 25% of cytogenetic deletion with R-bands routine cytogenetic analysis. We know that all cases with a microdeletion are put in evidence with in situ hybridyzation with Elastine probe located in chromosome 7q11.2, the region of Williams syndrome. We compare our cytogenetic results with other centres in Quebec working with G-bands cytogenetic routine analysis, they never see the deletion with their cytogenetic routine analysis. We can conclude that the use of R-bands is probably helpful revealing a chromosomal deletion in some cases of Williams syndrome. Up now, these patients do not show a different phenotype or behavior when they are compared with those ones they do not have the chromosomal deletion.
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Bérubé, D., Gagné, R. Williams syndrome: analysis by R-bands, G-bands and fluorescent in situ hybridyzation techniques. Genet Med 1, 67 (1999). https://doi.org/10.1097/00125817-199901000-00101
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DOI: https://doi.org/10.1097/00125817-199901000-00101