Reports dating back half a century have suggested that people with Down syndrome may have a reduced risk of breast cancer, colon and other cancers. The reason has been a mystery, but some researchers think it has to do with one or more of the genes on chromosome 21 that people with Down syndrome have three copies instead of the normal two. A new study supports this idea, linking a gene that is triplicated in Down syndrome with a lower risk of colon cancer in mice.
geneticists Thomas Sussan Johns Hopkins Bloomberg School of Public Health and Roger Reeves of Johns Hopkins School of Medicine, both in Baltimore, Maryland, and colleagues mated mice prone to colon cancer with mouse commonly used to model the Down syndrome. These mice have extra copies of genes 108 - about half as many triplets genes as in Down's syndrome. Offspring who inherited tripled genes and genetic susceptibility to cancer had only half the number of intestinal tumors as their parents predisposed to cancer and tumors that did develop were smaller, the team reports in the January 3 issue of Nature [
additional experiments with several other strains of mice have suggested that a gene called Ets2 - whose human counterpart is triplicated in people with the syndrome Down - accounts for much protection. Ironically, Reeves said, Ets2 has already been identified as a promoter of cancer. He can not explain why having an extra copy of the gene would produce the opposite effect. "I think it will be quite a complex thing to work," said Reeves, adding that Ets2 encodes a transcription factor that influences the activity of at least 0 other genes.
paradoxical finding a gene that promotes cancer in certain contexts can suppress other could have important implications for understanding and eventually treating, cancer in the general population, says geneticist David Threadgill University of North Carolina, Chapel Hill. "I think we need to reassess the way we look at many of these genes associated with cancer."
Related site
- Basic information about Down syndrome from the National Institutes of Health
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