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Human Genome News Archive Edition
Human Genome News, September 1994; 6(3):2
A team of some 45 researchers led by Mark Skolnick (University of Utah Medical Center and Myriad Genetics, Inc.) and Roger Wiseman (NIH National Institute of Environmental Health Sciences, North Carolina) reported on September 14 the isolation of the BRCA1 gene. Defective forms of BRCA1 are thought to cause predisposition to certain inherited forms of breast and ovarian cancer. Scientists have been searching for BRCA1 in a 600-kb region since 1990, when Mary-Claire King's group (University of California, Berkeley) demonstrated a pattern of genetic markers in families where breast cancer occurred unusually early and frequently.
Two papers describing the discovery appear in the October 7 issue of Science, and a separate study on the approximate location of another gene associated with breast cancer BRCA2 was published in the September 30 issue. The 100-kb BRCA1 gene is composed of 21 coding exons midway between markers D17S1321 and D17S1325 on the chromosome 17 long arm. Isolation of this gene could lead to significant clues about the risk of developing cancer, not only of the breast and ovaries, but also of the colon and prostate gland.
Although these discoveries are considered very important for studying the disease and eventually developing new diagnostic tools and treatments, scientists warned that much work lies ahead. NIH Director Harold Varmus said at a press conference that breast and ovarian cancers are extremely complicated diseases that are probably affected by various genetic and environmental factors. Several NIH entities, led by the National Center for Human Genome Research, have recently awarded research groups more than $2.5 million to study breast cancer testing and the social, psychological, and economic implications of such tests.
More than 45,000 U.S. women and 300 men died of breast cancer last year. BRCA1 is linked to about 5% of the 180,000 breast cancer cases diagnosed annually in the United States and to 25% of those in women under the age of 30. About 600,000 U.S. women and millions around the world may carry BRCA1 mutations.
BRCA1 is believed to act as a tumor suppressor regulating cell growth and division. If suppressor genes are lost or damaged by mutation, uncontrolled cell growth can occur, resulting in cancer. Researchers reported finding several different mutations in all family members who inherited the faulty BRCA1 gene and in those who developed breast cancer at an early age; they also observed the mutation in many women with both breast and ovarian cancers. Before diagnostic tests can be developed to detect the aberrant gene, each specific mutation must first be identified.
Although inheriting a mutated BRCA1 gene was found to increase dramatically the chance of developing breast cancer, scientists do not yet understand why only 15% of such women escape cancer, even in extreme old age. This suggests that even susceptible women may be influenced by crucial genetic or environmental factors. Identifying these factors will be critical in developing prevention strategies.
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Human Genome Program, U.S. Department of Energy, Human Genome News (v6n3).
The Human Genome Project (HGP) was an international 13-year effort, 1990 to 2003. Primary goals were to discover the complete set of human genes and make them accessible for further biological study, and determine the complete sequence of DNA bases in the human genome. See Timeline for more HGP history.
Published from 1989 until 2002, this newsletter facilitated HGP communication, helped prevent duplication of research effort, and informed persons interested in genome research.