However, in their study, researchers noted that this segmental duplication may encourage the type of genetic deletions that cause disease, as appears to be the case with the chromosomal region implicated in Williams-Beuren syndrome.
The syndrome, which is characterized by growth deficiency, heart disorders and mild mental retardation, is associated with very large deletions in a region of the long arm of chromosome 7 a region that the new analysis also found to be a hotbed of duplicated segments. Based on previous, smaller-scale studies, genetic scientists know that such duplicated segments, or duplicons, serve to encourage large-scale deletions and other dramatic rearrangements of genetic material. It is also known that, in addition to their potential to cause disease by disrupting genes, such genetic rearrangements may on rare occasions be beneficial by facilitating the formation of new genes.
Richard K. Wilson, Ph.D., director of the Washington University School of Medicine's Genome Sequencing Center and lead author of the study, said, "Our findings underscore the dynamic nature of the human genome and reveal how sequence structure may provide us with new insights into the genetic basis of human disease. But this analysis also drives home the fact that we still have a long way to go that we are just taking our first steps down the pathway to understanding the complicated interplay of genomics and health. Each chromosome that we analyze will likely add a new twist or turn."
In their analysis of the highly polished reference sequence, Dr.Wilson and
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Contact: Geoff Spencer
spencerg@mail.nih.gov
301-402-0911
NIH/National Human Genome Research Institute
9-Jul-2003