BOSTON -- Scientists have discovered that a mutant gene linked to several common cancers can be passed from parent to child, explaining how some families seem to be cursed with breast cancer and other malignancies.
Now that scientists know how the astonishingly high cancer risk passes from one generation to the next in the rare Li-Fraumeni syndrome, scientists said yesterday, that genetic mechanism may serve as a model for less dramatic but more common examples of unusual susceptibility to cancer.
"It is my guess that the small number of families" with the syndrome "represents only the tip of a much larger iceberg, and that other forms" of the inherited mutant gene, known as P53, "will be shown to be involved in other familial cancers," said Robert Weinberg, a specialist in cancer genetics at the Whitehead Institute in Cambridge.
The mutant P53 gene had been known to appear in several types of tumor cells, but in these cases the genetic damage appeared to have occurred during the patient's lifetime.
Today's report in the journal Science is the first to demonstrate that the mutant gene can be present at birth in all of a person's cells.
A cell usually has two copies of the gene, which plays a crucial cancer-suppressing role. Because patients with the syndrome are born with one of the two copies crippled, any damage to the second copy can set the stage for developing cancers, including breast cancer and at least six other types of tumors, said Stephen Friend of the Massachusetts General Hospital Cancer Center, senior author of the report in the journal Science.
As with other recent genetic advances, identification of the genetic flaw is expected to raise troubling questions of how to use that knowledge. A test is possible so members of families can learn whether they carry the gene.
"The benefit one could derive is to test the families who want to be tested and to tell some people that you don't have the gene and therefore go in peace," said Frederick Li, a cancer epidemiologist at Dana-Farber Cancer Institute and one of the scientists for whom the syndrome is named.
But such knowledge also carries the chance for psychological stress, as well as employment and insurance discrimination against gene carriers, he said. "If we don't proceed in a very careful manner, there could be harm."