People with Dawn’s Syndrome have a third copy of chromosome 21. This extra copy gives them extra versions of 231 different genes. Researchers from Harvard University found out that people with Dawn's Syndrome rarely get many kind of cancer except leukemia. Their hypothesis is that the third copy of chromosome 21 has copies of gene that help to regulate cancer growth. They carried out a study on more than 18000 patients with Dawn’s Syndrome and it showed only 10% of then is expected rate of cancer.
The experiment had been done by using induced Pluripotent Stem cell (iPS cell) from a volunteer with Dawn’s Syndrome and genetically engineered (GE) mice. The iPS cells are made from skin cells but have ability to perform like a stem cell. As results, the researchers succeeded to locate one gene that responsible to protect the GE mice against tumor. The gene is Dawn’s Syndrome Candidate Region-1 (DSCR1 or as known as RCAN1). This gene codes for a gene that suppresses vascular endothelial growth factor (VEGF). This protein is a necessary compound for angiogenesis of tumor cells. The transcription of VEGF is inhibiting by DSCR1 and hence no angiogenesis process occur. Down’s Syndrome patients have extra copy of DSCR1 gene in their genome. In the experiment, GE mice that are resistant to tumor also carry this extra gene. It is believe that there are other useful genes in this extra chromosome 21 and researchers are looking forward to explore more.
Glossary
iPS cell - A differentiated cell that has been modified so that it regains its ability to develop into other types of cell.
Angiogenesis - blood vessel formation. Tumor angiogenesis is the growth of blood vessels from surrounding tissue to a solid tumor. This is caused by the release of chemicals by the tumor.
reference:
www.reuters.com/article/healthNews/idUSTRE54J5IN20090520
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08062.html
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