The genomic basis of the Williams-Beuren syndrome.
The Williams-Beuren syndrome is a genomic disorder (prevalence: 1/7,500 to 1/20,000), caused by a hemizygous contiguous gene deletion on chromosome 7q11.23. Typical symptoms comprise supravalvular aortic stenosis, mental retardation, overfriendliness and visuospatial impairment. The common deletion sizes range of 1.5-1.8 mega base pairs (Mb), encompassing app. 28 genes. For a few genes, a genotype-phenotype correlation has been established. The best-explored gene within this region is the elastin gene; its haploinsufficiency causes arterial stenosis. The region of the Williams-Beuren syndrome consists of a single copy gene region (approximately 1.2 Mb) flanked by repetitive sequences--Low Copy Repeats (LCR). The deletions arise as a consequence of misalignment of these repetitive sequences during meiosis and a following unequal crossing over due to high similarity of LCRs. This review presents an overview of the Williams-Beuren syndrome region considering the genomic assembly, chromosomal rearrangements and their mechanisms (i.e. deletions, duplications, inversions) and evolutionary and historical aspects.
Schubert
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Institute of Human Genetics, Georg-August-University of Goettingen, Heinrich-Dueker-Weg 12, 37073 Goettingen, Germany. cschube@gwdg.de
D002869:Chromosome Aberrations; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics; D017353:Gene Deletion; D018628:Gene Dosage; D015894:Genome, Human; D006801:Humans; D018980:Williams Syndrome / Q000235:genetics*