Abstract for presentation at 11th International Congress of Human Genetics

Williams-Beuren syndrome: Additional atypical clinical symptoms and deletion size

  • Rafael Camara, Division of Medical Genetics, University Children's Hospital Basel, Switzerland
  • Karl Heinimann, Division of Medical Genetics, University Children's Hospital Basel, Switzerland
  • Friedel Wenzel, Division of Medical Genetics, University Children's Hospital Basel, Switzerland
  • Nemya Boesch, Division of Medical Genetics, University Children's Hospital Basel, Switzerland
  • Peter Miny, Division of Medical Genetics, University Children's Hospital Basel, Switzerland

    • Fluorescence in situ hybridisation (FISH) using commercially available probes confirmed a deletion within the Williams-Beuren syndrome critical region (WBSCR) of band 7q11.2 in a 2 year old proposita. The diagnosis was missed when she was first seen after delivery because of unilateral microphthalmia, bilateral clefts of the hard and soft palate, Pierre Robin sequence, as well as patent foramen ovale and ductus arteriosus. The chromosome count was normal and microdeletions in region 22q11 were excluded. She had been born spontaneously with normal measurements after a bleeding episode at 6 to 8 weeks of gestation. A maternal uncle was known to have a bifid uvula. The proposita later underwent surgery for bilateral inguinal herniae. At the age of two years typical facial features of the WBS were obvious. In order to assess the deletion size we investigated microsatellites from the WBSCR (D7S672, D7S489B, D7S2476, D7S1870, D7S489A, D7S2490, D7S2518, D7S2470, D7S669) in the proposita, two further patients with typical WBS as well as all parents. The deletion size in the proposita did not exceed the one in the two other patients and corresponded well to a minority of published cases with larger than average deletions. The paternal allele was deleted in the proposita while the maternal alleles were affected in both controls. A preliminary review of published patients with larger deletions showed no comparable clinical symptoms. To the best of our knowledge microphthalmia has not been reported in patients with WBS and cleft palate in a single patient only with an undetermined deletion size. We conclude that cleft palate and unilateral microphthalmia are probably not related to the deletion in the WBSCR and rather represent a chance occurence. We have not been able, however, to identify a deletion of similar size affecting the paternal allele among published case reports.

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