An international team of scientists is homing on the site of a third gene that might be involved in the development of hereditary breast cancer. If the gene is found, the work will pave the way to improved genetic counseling and cancer screening and treatment for family members with breast cancer history.
The shortcomings of so-called "susceptibility genes" contribute to the development of 5% to 10% of all breast cancers, which greatly increases the risk of contracting the disease from a woman. In to date, researchers have identified two genes predisposing to breast cancer, called BRCA1 and BRCA2 , but faults in these genes probably represent no more than one third of all hereditary breast cancer.
to track other susceptibility genes, research teams from Finland, Sweden, Iceland and the United States have joined forces. They identified 37 families that are affected with high rates of breast cancer, but who are not known BRCA1 or BRCA2 mutations. using a technique called comparative genomic hybridization of tumor DNA and normal tissue of 61 women, researchers found five probable areas for breast cancer genes. To refine their search, dim teams throughout these regions using two new mathematical models. Finally, they drew on the well-established methods of genotyping and linkage analysis to identify similar DNA segments shared by patients with breast cancer in a family.
Together, these techniques have given a region on chromosome 13 as the probable site of a third susceptibility gene, the teams reported in the August 15 Proceedings of the National Academy of Sciences . While it may take months to years to identify the faulty gene, this work is "an important intermediate step in seeking the reduction," said team member Olli Kallioniemi, a geneticist cancer in National Institute of research on the human genome in Bethesda, Maryland.
other scientists welcomed the announcement carefully, however. population geneticist mark Skolnick, scientific director for Myriad Genetics Inc. of Salt Lake City, which led the team that identified BRCA1 , finds the work "potentially very important," but warns that the statistical data are not conclusive.
Mary-Claire King, a geneticist at the University of Washington, Seattle, pioneered research of genes predisposing to breast cancer, leases integrative approach of the teams. But she noted that both Skolnick and BRCA2 also lies on chromosome 13. It is possible, they note that undiscovered faults around this gene may have confused the analysis. definitive proof that the team had indeed found a new gene linked to breast cancer, they say, will not come until researchers reproduce their work in other family groups or find gene itself.
Related Sites
The NCI's information page on Breast Cancer (CancerNet)
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