Team nabs second breast cancer gene.Last year, when an international team ended a 4-year quest for Verb 1. quest for - go in search of or hunt for; "pursue a hobby" quest after, go after, pursue look for, search, seek - try to locate or discover, or try to establish the existence of; "The police are searching for clues"; "They are searching for the the gene responsible for inherited breast cancer, the researchers announced that they and another team, working together, had discovered a second breast cancer gene breast cancer gene(s) See BRCA1, BRCA2. somewhere on the long arm of chromosome 13. Now, that second team, headed by Michael R. Stratton, has the additional gene in hand. Approximately 90 percent of all inherited cases of breast cancer can be attributed to mutations in either of the two genes. "We don't have all of [the second gene] because it is quite large," says Stratton, of the Institute of Cancer Research in Sutton, England. "But we do have the abnormalities which are responsible for breast cancer risk." In 1990, Mary-Claire King, now of the University of Washington in Seattle, reported that a breast cancer susceptibility gene dubbed BRCA BRCA One of two genes (designated BRCA1 and BRCA2) that help repair damage to DNA, but when inherited in a defective state increase the risk of breast and ovarian cancer. resides on chromosome 17 and may cause the 5 to 10 percent of breast cancers that are inherited. Last year, a team headed by Mark H. Skolnick of the University of Utah The University of Utah (also The U or the U of U or the UU), located in Salt Lake City, is the flagship public research university in the state of Utah, and one of 10 institutions that make up the Utah System of Higher Education. School of Medicine in Salt Lake City isolated the chromosome 17 gene and called it BRCA1. At the same time, Skolnick and Stratton had acquired evidence of another gene, on chromosome 13, that they called BRCA2 (SN: 9/24/94, p.197). Stratton and his group studied six families with a history of breast cancer linked to chromosome 13. In the Dec. 21/28 Nature, they report that each of those families harbors one of five mutations that truncate To cut off leading or trailing digits or characters from an item of data without regard to the accuracy of the remaining characters. Truncation occurs when data are converted into a new record with smaller field lengths than the original. the protein produced from BRCA2's instructions. Currently, Stratton's team has identified 7,000 of the gene's base pairs. The researchers suspect, however, that the entire BRCA2 gene could include as many as 12,000 base pairs. While BRCA2 bears only a slight resemblance to BRCA1, early evidence indicates that it, like BRCA1, provides the blueprint for a tumor suppressor sup·pres·sor n. 1. or sup·press·er One that suppresses: a suppressor of free speech. 2. A gene that suppresses the phenotypic expression of another gene, especially of a mutant gene. that puts a brake on cell growth. Inheriting mutations in either BRCA1 or BRCA2 gives a woman an 85 percent chance of developing breast cancer. Both genes also increase a woman's risk of ovarian cancer ovarian cancer Malignant tumour of the ovaries. Risk factors include early age of first menstruation (before age 12), late onset of menopause (after age 52), absence of pregnancy, presence of specific genetic mutations, use of fertility drugs, and personal history of breast , compared to the general population. BRCA1 confers a greater risk than BRCA2; however, BRCA2 mutations are responsible for some male breast cancers, whereas BRCA1 mutations are not. Stratton notes that isolating BRCA2 now allows researchers to explore the differences between the breast cancer genes. |
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