A study in the May 21 Nature reveals that surplus of cancer-suppressing proteins formed in cases of Down syndrome is the reason why cancer is so rare in the ones affected by this syndrome.

People born with Down syndrome have an extra copy of chromosome 21, instead of the usual two copies, one from each parent, and thus they inherit 231 extra genes.

A tumor requires veins and arteries to nurture its rapid growth. So tumors frame a haphazard cluster of new vessels that imitate a legitimate body process called angiogenesis.

Now, it has been found that one of the genes on chromosome 21 encodes a protein that blocks a factor needed for blood vessel growth and thus prevents angiogenesis. This gene, called DSCR1, is produced in excess in people with Down syndrome.

"I think there may be four or five genes on chromosome 21 that are necessary for angiogenesis suppression," says Sandra Ryeom, PhD, and colleagues at Children's Hospital Boston, who had designed a series of experiments on this phenomenon.

"It is, perhaps, inspiring that the Down syndrome population provides us with new insight into mechanisms that regulate cancer growth and, by so doing, identifies potential targets for tumor prevention and therapy," Ryeom and colleagues conclude.