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Anti-Angiogenesis Genes May Contribute to Low Cancer Rate in Down Syndrome

Researchers have provided evidence that the extra copies of two chromosome 21 genes may be responsible, at least in part, for the extremely low cancer rate in those with Down syndrome. The rate of cancer in Down syndrome individuals is lower than 10 percent of that in the general population. It had been proposed that because Down syndrome individuals have an extra copy of chromosome 21, that there may be one or more cancer-protective genes on this chromosome. The late cancer researcher Dr. Judah Folkman proposed that the extra copy of chromosome 21 may contain a gene that blocks angiogenesis, the development of blood vessels essential for cancer's growth. In the current experiments, scientists showed that a single extra copy of the chromosome 21 gene Dscr1 is sufficient to significantly suppress angiogenesis and tumor growth in mice, as well as angiogenesis in human cells. The team also found that levels of DSCR1 protein are elevated in tissues from people with Down syndrome and in a mouse model of the disease. The extra copy of another chromosome 21 gene, Dyrk1A, also appeared to decrease cells' response to an angiogenesis-promoting protein. "I think there may be four or five genes on chromosome 21 that are necessary for angiogenesis suppression," said Dr. Sandra Ryeom, the senior author of the report. "In huge databases of cancer patients with solid tumors, there are very few with Down syndrome. This suggests that protection from chromosome 21 genes is pretty complete." This research was published online on May 20 in Nature. [Press release] [Nature abstract]