[Clinical aspects and genetics of Williams-Beuren syndrome. Clinical and molecular genetic study of 44 patients with suspected Williams-Beuren syndrome].

BACKGROUND

The suspected diagnosis of Williams-Beuren syndrome (WBS), which is a retardation syndrome with great clinical variability, was cause for comparison of molecular genetic, molecular cytogenetic analysis to clinical symptoms. The results of the genetical analysis of a microdeletion of the elastin gene region on chromosome 7 were compared to the clinical symptoms. Are there any differences between symptoms in case of deletion or non-deletion? How informative are the molecular genetic, molecular cytogenetic analysis?

PATIENTS AND

METHODS

44 patients with suspected diagnosis of WBS were examined using molecular genetic and molecular cytogenetic methods. The clinical symptoms as general symptoms, heart anomaly, dysmorphic signs and unusual neurobehavioural features were reported during clinical investigation in standardized questionnaires. The genomic DNA of the patients and their parents was analyzed using microsatellite markers. In some cases (e.g. uninformative microsatellite studies) we also used fluorescence in situ hybridization (FISH) with an elastin gene probe and performed a conventional chromosome banding analysis.

RESULTS

15 patients had a microdeletion. 4 patients had a deletion of the paternal allel and 7 patients showed the deletion of the maternal allel. The polymorphisms were of limited informativeness. In 2 cases microsatellite analysis was not able to determine whether the paternal or the maternal allel had been lost. In 2 cases the microsatellite analysis was uninformative so that FISH analysis was performed. All FISH analysis performed had an informative result. 80% of the children with a microdeletion of chromosome 7q11.23 showed the typical dysmorphic signs, 70% exhibited the typical WBS behaviour pattern, 50% had a specific heart anomaly. In contrast, in the group of children without a chromosomal microdeletion only 30-40% showed typical dysmorphic signs, only 10% had a typical heart anomaly and none of them showed specific behavioural changes. We found no indication to association of specific symptoms with paternal versus maternal origin of the deletion. The FISH analysis combined with a conventional chromosome banding analysis is very informative for diagnostic values. The results are compared to data of literature.

CONCLUSIONS

Children with developmental retardation and WBS dysmorphic signs and an unusual behaviour should be examined by a molecular cytogenetic FISH analysis. If a microdeletion of band 7q11.23 is found a special cardiologic examination should be offered.